in 2 Tim 2:12 says that if we deny Jesus and He will deny us. In what sense is denial meant? Does this include believers, or just those who reject salvation through faith in Jesus?
The Greek word translated deny means to not accept, to reject, or to refuse something offered.
Believers cannot deny Jesus because we’ve already accepted Him. Once we did that God marked us with a seal, the promised Holy Spirit who is a deposit guaranteeing our inheritance (Ephes. 1:13-14). Therefore Paul was speaking only of unbelievers here.
Some English translations use the word disown” in 2 Tim 2:12, but the Greek word is never translated that way, and it changes Paul’s meaning because to disown means to renounce or repudiate. This would have Paul saying we could reject the Lord after claiming to be one of His, which would contradict his other statements on salvation, like the one above.