Denying the faith:
They profess to know God, but by their deeds they deny Him, being detestable and disobedient and worthless for any good deed. (Titus 1:16)
For the love of money is a root of all sorts of evil, and some by longing for it have wandered away from the faith and pierced themselves with many griefs. (1 Timothy 6:10)
But the Spirit explicitly says that in later times some will fall away from the faith, paying attention to deceitful spirits and doctrines of demons, (1 Timothy 4:1)
keeping faith and a good conscience, which some have rejected and suffered shipwreck in regard to their faith. (1 Timothy 1:19)
But if anyone does not provide for his own, and especially for those of his household, he has denied the faith and is worse than an unbeliever. (1 Timothy 5:8)
O Timothy, guard what has been entrusted to you, avoiding worldly and empty chatter and the opposing arguments of what is falsely called "knowledge"— which some have professed and thus gone astray from the faith. Grace be with you. (1 Timothy 6:20-21)
holding to a form of godliness, although they have denied its power; Avoid such men as these. For among them are those who enter into households and captivate weak women weighed down with sins, led on by various impulses, always learning and never able to come to the knowledge of the truth. Just as Jannes and Jambres opposed Moses, so these men also oppose the truth, men of depraved mind, rejected in regard to the faith. (2 Timothy 3:5-8)
“Who is the liar but the one who denies that Jesus is the Christ? This is the antichrist, the one who denies the Father and the Son.” (1 John 2:22)
“The one who says, "I have come to know Him," and does not keep His commandments, is a liar, and the truth is not in him;” (1 John 2:4)
Examples:
“And Peter remembered the word which Jesus had said, "Before a rooster crows, you will deny Me three times." And he went out and wept bitterly.” (Matthew 26:75)
“keeping faith and a good conscience, which some have rejected and suffered shipwreck in regard to their faith. Among these are Hymenaeus and Alexander, whom I have handed over to Satan, so that they will be taught not to blaspheme.” (1 Timothy 1:19-20)
“But Jesus said to him, "Judas, are you betraying the Son of Man with a kiss?"” (Luke 22:48)
for some (believers) have already turned aside to follow Satan. (1 Timothy 5:15)
men who have gone astray from the truth saying that the resurrection has already taken place, and they upset the faith of some. (2 Timothy 2:18)
Consequences:
“If we endure, we will also reign with Him; If we deny Him, He also will deny us;” (2 Timothy 2:12)
“"But whoever denies Me before men, I will also deny him before My Father who is in heaven.” (Matthew 10:33)
“but he who denies Me before men will be denied before the angels of God.” (Luke 12:9)
“"And then I will declare to them, 'I never knew you; DEPART FROM ME, YOU WHO PRACTICE LAWLESSNESS.'” (Matthew 7:23)
“"Then He will also say to those on His left, 'Depart from Me, accursed ones, into the eternal fire which has been prepared for the devil and his angels;” (Matthew 25:41)
“and He will say, 'I tell you, I do not know where you are from; DEPART FROM ME, ALL YOU EVILDOERS.'” (Luke 13:27)
Confessing Him:
“"Therefore everyone who confesses Me before men, I will also confess him before My Father who is in heaven.” (Matthew 10:32)
“"And I say to you, everyone who confesses Me before men, the Son of Man will confess him also before the angels of God;” (Luke 12:8)
“The one who believes in the Son of God has the testimony in himself; the one who does not believe God has made Him a liar, because he has not believed in the testimony that God has given concerning His Son.” (1 John 5:10)
“By this you know the Spirit of God: every spirit that confesses that Jesus Christ has come in the flesh is from God; and every spirit that does not confess Jesus is not from God; this is the spirit of the antichrist, of which you have heard that it is coming, and now it is already in the world.” (1 John 4:2-3)
“Beloved, while I was making every effort to write you about our common salvation, I felt the necessity to write to you appealing that you contend earnestly for the faith which was once for all handed down to the saints.” (Jude 1:3)
Examples:
“'I know where you dwell, where Satan's throne is; and you hold fast My name, and did not deny My faith even in the days of Antipas, My witness, My faithful one, who was killed among you, where Satan dwells.” (Revelation 2:13)
“'I know your deeds. Behold, I have put before you an open door which no one can shut, because you have a little power, and have kept My word, and have not denied My name.” (Revelation 3:8)
Rewards:
“that if you confess with your mouth Jesus as Lord, and believe in your heart that God raised Him from the dead, you will be saved; for with the heart a person believes, resulting in righteousness, and with the mouth he confesses, resulting in salvation. For the Scripture says, "WHOEVER BELIEVES IN HIM WILL NOT BE DISAPPOINTED."” (Romans 10:9-11)
“Whoever denies the Son does not have the Father; the one who confesses the Son has the Father also.” (1 John 2:23)