1 JOHN 1:9 NKJ
9 If we confess our sins, He is faithful and just to forgive us our sins and to cleanse us from all unrighteousness.
This is the only verse under the New Covenant that mentions confession of sins to God.
The meaning of the Greek word here translated "confess" is "to say the same thing as another, i.e. to agree with."
So replacing the word "confess" in the verse with its meaning, gives us this:
1 JOHN 1:9
9 If we (say the same thing as God about) our sins, He is faithful and just to forgive us our sins and to cleanse us from all unrighteousness.
So let's see what God has said about our sins under the New Covenant, so we can say the same thing as He has said about them.
HEBREWS 8:12-13 NKJ
12 "For I will be merciful to their unrighteousness, and their sins and their lawless deeds I will remember no more."
13 In that He says, "A new covenant," He has made the first obsolete. Now what is becoming obsolete and growing old is ready to vanish away.
HEBREWS 10:16-17 NKJ
16 "This is the covenant that I will make with them after those days, says the LORD: I will put My laws into their hearts, and in their minds I will write them,"
17 then He adds, "Their sins and their lawless deeds I will remember no more."
Since God says He does not remember our sins, is it polite or wise to keep bringing them up to Him?
1 JOHN 2:12 NKJ
12 I write to you, little children, Because your sins are forgiven you for His name's sake.
EPHESIANS 1:7 NKJ
7 In Him we have redemption through His blood, the forgiveness of sins, according to the riches of His grace
This says we have the forgiveness of sins. There is no need to ask for something you already have. Doing so is disrespectful to the One who has given you forgiveness.
COLOSSIANS 2:13 NKJ
13 And you, being dead in your trespasses and the uncircumcision of your flesh, He has made alive together with Him, having forgiven you all trespasses,
2 CORINTHIANS 5:19 NKJ
19 that is, that God was in Christ reconciling the world to Himself, not imputing their trespasses to them, and has committed to us the word of reconciliation.
God reconciled the world to Himself in Christ and He is no longer holding our sins against us (which is what imputing means).
In Christ, God extended complete and total forgiveness for all the world. He is not holding the sins of anyone against them. For God to do so would be unjust, because Jesus already suffered the penalty for all sin.
Yet we must receive God's forgiveness for it to benefit us. God did His part, now we must respond in faith and be reconciled to God.
2 CORINTHIANS 5:20-21 NKJ
20 Now then, we are ambassadors for Christ, as though God were pleading through us: we implore you on Christ's behalf, be reconciled to God.
21 For He made Him who knew no sin to be sin for us, that we might become the righteousness of God in Him.
For us to beg God for forgiveness is rude. God already said He has forgiven. Now it is up to us to believe and accept His forgiveness.
(Showing remorse for our sin is not wrong. Remorse is what many people think of as repentance, but actually repentance means a change in thinking which results in a change of action. Remorse is not required for true Biblical repentance.)
Using the definition of what the word confess means, here is one example of a correct way to confess sin.
"Lord Jesus, what I did was a sin. Thank You for already paying the price for that sin on the cross. Thank You for loving me and suffering the punishment so I can go free. Thank You God that I have been forgiven and cleansed by the blood of Jesus. Sin is deadly so please work in me and help me to stop it."
Asking God to forgive you is not New Covenant confession of sin, because God says you are already forgiven. Don't ask God to do something He has already done! Instead, acknowledge the sin was wrong and thank Him for forgiveness and cleansing by the precious blood of Jesus.
SAY THIS: If I sin, I will agree with what God says about it.