Clearly the One who was manifested in the flesh, preached among the Gentiles, and received up in glory (after His resurrection) was Jesus. But where, there may be, and has been controversy, is whether the verse says “God was manifested in the flesh” or something else.
Here are what the various translations (which I have on my Online Bible Program) have for the word:
God—Av, Darby, NKJV, EMTV, RWebster, WEB, YLT
He—ASV, ESV, HCSB, LO, WASB, RSV, Williams
If we were to judge by majority translations, then it may be a tie between “God” and “He.” However, that would be a poor attempt a solution to the problem. It’s all a matter of what the apostle Paul wrote in the original Greek text. But, as we know, that doesn’t exist for ANY part of the New Testament. We have only copies. Unfortunately, none of the extant manuscripts prior to A.D. 300, contains either of Paul’s letters to Timothy.
In all manuscripts that DO contain the verse there are two, and only two variations of the word. One of these variations is “OC,” that is, the two letters omicron and sigma (All early copies of the New Testament writings were written in upper-case Greek letters). The other variation is ΘC with a bar over the two letters (I don’t know how to do this in a post).
Now “OC” is a relative pronoun in Greek, and means “who” or “which,” whereas ΘC with a bar over the two letters, is an abbreviation for ΘΕΟC (theos) which means “God.”
There are many extant manuscripts that contain “OC” (who, which) in the verse, and also many contain ΘC with a bar over the two letters. If we are going to accept the former, we need to use the translation “who” or “which”, and if the latter, we need to use the translation “God.” But “who” is a relative pronoun and if it is correct, then the pronoun doesn’t seem relative to anything. Where is its antecedent? The verse is clearly referring to Jesus who was “received up in glory” when God raised Him from the dead. But if Jesus is the antecedent you have to go way back to chapter 2, verses 5 and 6—and there is a whole lot in between in which Paul gives various instructions to overseers, deacons, and their wives. So the word cannot mean “who.” Well, how about “which” as the Douay and Murdoch translate it? At least the antecedent is obvious. You would have, “the mystery of godliness, which was manifested in the flesh.” But does that make any sense? How can the mystery of godliness be manifested in the flesh, and be received up in glory?
Those translations that render the word as “He” are incorrect. The relative pronoun “OC” never means “he.”
As I see it, ΘC with a bar over the two letters, an abbreviation for ΘΕΟC (theos) is correct. But there is no article before the word. So it does not refer to the Father, or the “only true God” as Jesus addressed Him. It may mean “God” in the same sense as it’s second occurrence is used in John 1:1. In that verse, the Word is with “the God” (the only true God), and the word was God generically. When we generate children each of them is “man” generically. Whether the child is a boy or a girl, he or she is man. In the same way, The Father’s only Son is God.
Your child is not bovine or feline, or canine; it is human like its parents. When God generated His only Son, that Son was not bovine, feline, canine, or human. He was divine like His parent. However though God begot Him as His only divine offspring, He appointed Him to BECOME fully human—to be born as a man—to divest Himself of all His divine attributes, and become a true human being:
The only thing that Jesus retained of His pre-existence, was His identity as the Son of God.