What does 1 Timothy 4:9 mean?

The prior verse encouraged Timothy, and other Christians, to pursue spiritual "training." This process of learning, teaching, and living out the word of God is critical for the health and growth of the church. To emphasize this importance, Paul has just indicated that this spiritual "exercise" is more useful than the exercise an athlete gives to their physical body. Bodily fitness is temporary, but spiritual fitness lasts for eternity.

So, here the statement Paul is encouraging Timothy to fully accept is the prior verse. Believers are to strive for godliness, because it has impact both in this life and the next. The phrase "the saying is trustworthy," is unique to the Pastoral Epistles in the New Testament, used five times by Paul. He also uses the phrase in 1 Timothy 1:15 and 1 Timothy 3:1, as well as 2 Timothy 2:11 and Titus 3:8. Each time, the phrase emphasizes a particular point or quote Paul wants Timothy or Titus to remember.

The second part of this phrase, "deserving of full acceptance," is repeated elsewhere only in 1 Timothy 1:15, where Paul emphasized that "Christ Jesus came into the world to save sinners, of whom I [Paul] am the foremost." Just as Timothy was to fully accept the fact that Paul was a sinner saved by God's grace, he was also to accept that godliness or spiritual training was important now and for eternity.