If 2 Timothy 2 is meaning what you think it means, then how did Peter end up being an apostle?
We endure because at the New Birth, Christ is IN us - that is why when we are unfaithful, He is faithful - He cannot deny Himself - we are ONE with Him. If we died with Him . . . then we will also live with Him . . . the New Birth - New Life - New Creation.
20 I have been crucified with Christ and I no longer live, but Christ lives in me. The life I now live in the body, I live by faith in the Son of God, who loved me and gave himself for me. 21 I do not set aside the grace of God, for if righteousness could be gained through the law, Christ died for nothing!” (from Galatians 2)
Again, we always need to remember Who Jesus is, what He came to do, what that actually accomplished, and who we are in Him. Through that lens interpreting seemingly contradictory passages is a lot easier.
-JGIG