Denial of truth is rejection of truth. Confession is the opposite of denial. (John 1:20).
The Bible tells us that God will deny us if we deny Him (2Tim.2:12; Matt.10:23; Luke 12:9).
Denial of God can be done
1. In words (Prov.30:9)
2. In works (Tit.1:16)
(see also Jude 1:4; Rev.2:13)
The one who denies Christ
1. Is a liar (1Jn.2:22)
2. Is antichrist (1Jn.2:22)
3. Does not have the Father (1Jn.2:23)
In the case of Peter's denial of Christ three times, the Lord restored him because he denied out of fear and repented with great remorse (Matt.26:75). Also, he did confess his love for Christ after Christ's resurrection (Jn.21:14ff). Peter became one of the strongest witnesses of Christ's resurrection (Acts 5:29-32).
Jesus calls us to deny ourselves and follow Christ (Luke 9:23). To deny self means to say "no" to our own will and desires and to surrender in obedience to the will of Christ.