The Bible was written in the plain language of the communities in which the writers lived. Sometimes the language was used metaphorically, but the words themselves always were ordinary words from everyday life. In particular the Hebrew of what Christians call the Old Testament is particularly earthy and full of puns that do not translate into European languages. Similarly in the New Testament an Aramaic pun on the word for "rock" was translated still as a pun into Greek, and again as a pun into Latin, and from there into the Romance languages, but the pun was for some reason not translated into English so we are left with "You are Peter and on this rock I will found my church." By contrast the original Aramaic pun remains in French "Tu es Pierre, et sur cette pierre Je fonderai mon église." The Gospel of John explains the origin of the nickname of Shimon (Greek did not have a "sh" sound so it was replaced with "s"), the son of Iona (John) and brother of Andrea (Andrew) as coming from the Aramaic כֵּיפָא (kepha), a stone or rock. The "s" is added to the end of this masculine name in Greek, just as it is when the Aramaic ישוע Yeshua is spelled Ἰησοῦς (Iēsous), because in Greek all masculine nouns end with an "s" when used as the subject of a sentence. The pun is not perfect in Greek (Πέτρος vs. Πέτρα), or Latin (Petrus vs. petra) because the word for "rock" in both languages is feminine whereas it was masculine in Aramaic. Imagine casting Dwayne Johnson in the role of St Peter and having the actor playing Jesus say "You are The Rock, and on this rock I will found my church." I apologize to World Wrestling Entertainment for the use of their trademark.
However translations of religious documents, particularly into English, even those which claim to be in plain language typically use traditional vocabulary that not only obscures the original everyday meaning of the words but moreover has created misunderstandings because those words have popular interpretations which are very different from both those original everyday meanings and more importantly from the clear intention of the original writers.
The most controversial aspect of Christian theology is the concept of the Trinity: that the monotheistic deity has three "persons", the Father, Son, and the Holy Spirit. The oldest appearance of this formulas is in the baptismal formula by which an individual becomes a Christian, which is already attested in the first century CE. The popularity of the Jewish Shema and the Muslim profession of faith both may be interpreted as rejection of this multipart Christian God. To describe the aspects of the Trinity early Greek theologians used two words: πρόσωπα (prosopa) and ὑπόστασις (hypostasis). These words were translated by Tertullian into Latin as persona and substantia. The Greek prosopa literally means "in front of the face" and was the technical term for the theatrical mask worn by an actor when playing a role. A pair of such masks, one smiling and one frowning, are still used as a visual symbol for the theatre. Tertullian, in searching for a Latin equivalent chose persona, which is the Latin word for the mask worn by an actor when playing a role. But in everyday English, however, "person" normally means an individual and in particular in the law for a corporation which is treated like an individual. In English the idea that three "persons" could be an individual is ludicrous. Since the original word was theatrical the natural translation of the theological term into English should be "role", which retains the original theatrical concept. As Shakespeare points out "one man in his time plays many parts." So a monotheistic God can be imagined to play three roles in his/her relationship with mortals. The Greek hypostasis, literally "under state", derives from Platonic philosophy to represent the fundamental underlying nature of an object. But this distinction is only meaningful within Platonic philosophy since you first have to accept that an object has an underlying nature that is distinct from its physical existence. The vast majority of Christian theologians have subscribed to Platonic philosophy, although it is not clear why. None of the writers of the New Testament had any investment in Platonism, although some of them, for example Paul, had a vague familiarity with popular understanding of Platonism. There is nothing in the Bible to suggest that any of the authors had actually read Plato. For example the disagreement between the Roman Catholic Church and the Anglican and Lutheran Churches over whether the bread and wine are transformed into the body and blood of Christ, transubstantiation, or merely coexist with the body and blood of Christ, consubstantiation, has as a basic assumption that bread and wine can have an underlying substance, its hypostasis, which is distinct from its physical nature as bread and wine! But in English the normal meaning of substance is "a solid, powder, liquid, or gas with particular properties". That is in normal English substance is inseparable from the observable properties of an object. While theology students may get a basic introduction to Platonism at the seminary, it is unprofessional to expect that understanding from an audience which is more familiar with the Collins Dictionary definition given above.
The Hebrew word רוּחַ (ruach) and the Greek word πνεῦμα (pneuma) both have the plain meaning of "breath", as does spiritus, used by Tertullian and Jerome to translate those two words into Latin. Anyone discussing Judaism or Christianity at any time prior to the introduction of vernacular translations of the Bible automatically recognized the underlying meaning of "breath" every time they used these words. For example when the theologian Thomas Aquinas debated the morality of first trimester abortions he considered that since the lungs, necessary for breath, did not appear until the second trimester it was arguable that the soul might not enter into the child until breath, spiritus, was present. In choosing to translate all occurrences of רוּחַ, πνεῦμα, and spiritus, throughout the Bible and all theological discussions whether translated from Hebrew, Greek, and Latin, or written in English, as "spirit", a clearly invented word imported from Latin rather than using the plain language translation "breath" all English-speaking readers are given only part of the concept. Even worse is the translation used by the committee that created the King James or Authorized Version where πνεῦμα in the New Testament is consistently translated as "Holy Ghost", principally to retain the wording of William Tyndale's 1534 translation where it appears as "Holy Goost" (Tyndale used "oo" for a long "o"). But "ghost" has a normal English meaning of the disembodied manifestation of a deceased person! Note that in most translations of the New Testament πνεῦμα is translated as "Holy Spirit" even though it is not typically preceded by ἅγία (holy) in the original Greek. That is the translator has permitted trinitarian theology, developed in the 4th century of the Common Era (CE), to influence the translation of a document written in the 1st century CE.
A very common title in the Bible is "prophet". In Hebrew this was נָבִיא (nāvî), "spokesman", which was translated into the Greek Septuagint as προφήτης (prophetes) which again has the literal meaning "spokesman". As one of my teachers pointed out, "How do you tell if someone is a prophet? They start each statement with 'God Says...'." For example in Islam Muhammad is a nabiim (prophet) or rasul (messenger) who delivered the literal Word of Allah in the form of the Qu'ran. For some reason the 3rd century BCE was the last time anyone translated either of these words into any other language. In particular Jerome apparently could not find a Latin word that conveyed the sense of the Greek and Hebrew, although I do not know why he rejected proorator, so he just copied the Greek word, making only the minimal grammatical changes to conform to the rules of Latin, and every Western translation continues to use the Greek word "prophet". This was maybe acceptable as long as readers continued to understand Greek, but that knowledge died in the West by the 7th century CE. If you go to most English dictionaries you will find an official definition which agrees with the intention of the Scriptures, but the majority of English speakers, particularly in the United States of America, believe, regardless of the facts, that a prophet is someone who has divine foreknowledge of the future. This interpretation is almost entirely derived from a misunderstanding of the book of Daniel, a fictional novel written in 164 BCE as a criticism of the Greek ruler Antiochus Epiphanes who had erected a pagan statue within the Jewish Temple at Jerusalem. The book of Daniel was not considered by the Jews to be a prophetic book since it is not included in the section of the Old Testament which they call Naviim, the Prophets, but rather in the "miscellaneous" section they call Ketuvim, the Writings. There are references to a folk-hero named Daniel which precede the Babylonia captivity. Moreover the book of Daniel could not be contemporary with the story it tells because it misspells the name of the Babylonian king, who, as presented in the 2nd Book of Kings, was properly named Nebuchadrezzar. True spokespeople do not predict the future. What they declare is "God says that if you do this act that He disapproves of then the following undesirable result will occur." To avoid this misinterpretation every occurrence of נָבִיא (nāvî) or προφήτης (prophetes) should appear in an English Bible or religious commentary as the literal "spokes-person/man/woman".
Another untranslated Greek word which is consistently misinterpreted by modern English readers is "angel". In Hebrew this appears as מַלְאָךְ (mal’akh), literally a messenger, and is used for both divine and ordinary messengers. As pointed out in Wikipedia "In the King James Bible, the noun mal’akh is rendered "angel" 111 times, "messenger" 98 times, "ambassadors" 4 times." Mal’akh is the word for "angel" in Arabic (malak ملاك), Aramaic, and Ge'ez. For some reason the Greek ἄγγελος (angelos) which again just means "messenger", was left untranslated by Jerome, even though the ordinary Latin word nuntius was an option, and so the gibberish "angel" has passed into all Western language, The Seraphim, statues of which stood on either side of the Ark of the Covenant, had wings, but they were understood to appear as winged beasts, and were therefore similar to the winged chimeras which appear in Assyrian monuments. Humanoid angels did not have wings, and indeed were frequently only recognized as angels after the fact. Contrary to popular belief as depicted in movies and television shows angels are not deceased humans sent back to Earth but are an independent order of creation, agents of God who, while having greater powers than mere mortals because of their direct contact with God, lack human free will. For example the angel Jibril (جبريل, Gabriel) dictated the Qu'ran to the Prophet Muhammad word for word.
In the original Greek of the New Testament the immediate followers of Jesus are described as μαθητής (mathetes), literally "students". The same word is still used in Greece for a schoolboy. In Matthew and Mark the word is only used of "the twelve" whereas in Luke it is used also for other followers. When Jerome translated μαθητής into Latin he used discipulus, which again just means student. However instead of translating discipulus into normal English Tyndale rendered it as the gibberish word "disciple". Closely related is the Greek ἀπόστολος (apóstolos) literally meaning someone who is sent away. When Jerome translated the Bible into Latin instead of translating the sense of the Greek word, for example by using dimittans or missionarius, he simply adjusted the Greek word to conform to Latin grammer as apostolus. Again Tyndale left the "Latin" word untranslated except to adjust the spelling to represent the way he pronounced the word. Here as generally the KJV/RSV simply copied Tyndale, and so these two gibberish words were added to English language.
There are a lot of misunderstandings of Roman criminal procedure in the popular discussion of the execution of Jesus. The Romans did not have a "correctional system". For any crime they essentially had two punishments which focussed totally on deterrence: death by torture, crucifixio, and being sent to work in the mines, damnatio ad metalla, which was death by exhaustion, starvation, and heavy metal poisioning (particular from arsenic used in the purification process). In the 1st century CE the Latin word crux did not mean "cross" in the modern sense of an object with two wooden beams fixed at right angle, rather it was the noun associated with the verb cruciare, to torment or torture. At the time a crux was any wooden device that displayed the dieing convict such that his death would be as painful and prolonged and public as possible. The past participle of that verb, cruciatus, is retained in the word excruciating. However by far the most common form of crucifixion throughout history has been impalement. Impalement is documented in almost every Eurasian culture from the Law Code of Hammurabi in the 20th century BCE, again as descibed by Seneca the Younger a contemporary of Jesus (both born in 4 BCE), through its use by the Romanian patriot leader Vlad Țepeș in the 15th century CE in his campaign against the Turks. Wood suitable for constructing a crux was and is relatively scarce in the Mediterranean. The wooden posts at the apparently standard place of execution called Golgotha (in the Aramaic which was the daily language of Jerusalem, meaning "skull", translated into Greek as Κρανίου Τόπος, the "place of the skull", and then by Jerome into Latin as Locus Calvariae, the "place of the skull", from which it was simply transliterated into the gibberish English Calvary), were presumably permanent gibbets, described in the Greek as stauros, "stake". However in situations where mass crucifixions took place. for example after the 3rd Servile Revolt led by Spartacus in 71BCE and after the Jewish Revolt in 70CE, the prisoners were generally tied, not nailed, to trees every few hundred yards along major roads. Iron nails were very expensive and where used, as documented for the execution of Jesus for example, were pulled out and reused. These nails were not driven into the palms of the hand, since the weight of the convict might tear the hand free, rather they were driven through the wrist or between the two long bones of the forearm,and some times the feet were aligned so that a long nail could be driven through the two heels into the post, which would prolong the torment of death by delaying asphyxiation. The earliest comments on the death of Christ indicate the belief that there was a cross-beam on which his arms were out-stretched, but that this was attached to the top of the main post to form a T, not slotted part-way down the post as in most artistic and theatrical presentations. By the time that Jerome translated the New Testament into Latin from Greek in the 4th century CE it was a tradition among Christians that the vertical post extended above the cross-beam, but that would have complicated the construction and increased the required height of the post to no administrative advantage. Perhaps that extension was felt to be implied by the fact that the sign "Jesus the Nazarene, King of the Jews" was allegedly posted above him, as continues to appear in Roman Catholic crucifixes.