In many languages, it is usually considered poor literary practice to mix metaphors. Apparently, Paul was never acquainted with this idea as he quite often mixes his metaphors and even piles them up as in 2 Tim 4:7. Here Paul uses three metaphors, actually five if we include the previous verse as well:
- In v6 Paul equates himself with one of the temple practices of pouring out a drink offering, signifying his immanent death.
- In the same verse he re-emphasises this by using a travel metaphor and says that his departure is near, again meaning his death is immanent.
- In V7 the first metaphor is taken from an athletic fight contest and says that he has fought a good fight, meaning that he has put all his effort into his preaching and Christian life.
- The next metaphor is taken from the Olympic games - running a race which he says is now complete (see also Acts 20:24) meaning that his effort was over, that is, his death was immanent
- The next metaphor is taken from the idea of a prison or vault where something is guarded to prevent its loss - Paul has "kept the faith".
On this last verb, τετήρηκα (tetērēka), from the root form, τηρέω (téreó), BDAG defines (for this instance) the meaning, "to cause a state, condition, or activity to continue, keep, hold, reserve, preserve." More specifically, "of holding on to something, so as not to give it up or lose it". This all comes from the central idea of guarding something to prevent its loss. It is this that Paul claims to have done with "the faith".
Thus, Paul claims to have kept the faith and preserved it, unchanged, unblemished. That is, he did not change it. Ellicott observes here:
I have kept the faith.--Here, again, the metaphor is changed, and St.
Paul looks back on his lived life as on one long, painful struggle to
guard the treasure of the Catholic faith inviolate and untarnished
(see 1Timothy 6:20). And now the struggle was over, and he handed on
the sacred deposit, safe.