Actually, the verse does need to be read in context to grasp the full understanding of what the author is trying to say.
The chapter is about the need to pray for all people. The chapter starts with praying for leaders--good or bad. There must have been some debate over this which the author is compelled to emphasis that this is a good thing to do because God desires all people to be saved.
Then we come to the verse in question. At first glance, it would suggest that God and the "man Christ Jesus" are separate individuals--one leads to another. That phrasing is unusual. He doesn't just say "Christ", "Christ Jesus" or "Jesus Christ" as how he is typically called, but "man Christ Jesus". I'll come back to that in a bit.
If you continue on to verse 6, this "man Christ Jesus" is quantified with a reason for him being the "mediator", that is because he "gave himself as a ransom for all", which refers to Christ's death on the cross, which symbolizes the Jewish sacrificial requirement for the atonement of sin, but with Jesus, it was an over encompassing and everlasting sacrifice for all and for all eternity all to reunite man to God (salvation).
Obviously, as God, Jesus Christ, is divine and is alive. But for that moment, the physical man that served as the embodiment of Jesus Christ, had to die a physical death. It was the power of the Father and the divine nature of Jesus Christ that he was able to be resurrect back to life, but the physical man of Christ died. I can only surmise that is why the phrase of "man Christ Jesus" was quantified in such an explicit manner.
And it is through the physical death of human embodiment of Jesus Christ that serves as the testimony for which to bring people to salvation.