You are wrong.
Paul taught it...
“Knowing this, that our old man is crucified with him, that the body of sin might be destroyed, that henceforth we should not serve sin.For he that is dead is freed from sin.” (Rom. 6:6-7)
"Being then made free from sin, ye became the servants of righteousness." (Rom 6:18)
"But now being made free from sin, and become servants to God, ye have your fruit unto holiness, and the end everlasting life." (Rom 6:22)
"There is therefore now no condemnation to them which are in Christ Jesus, who walk not after the flesh, but after the Spirit." (Rom 8:1)
"Awake to righteousness, and sin not; for some have not the knowledge of God: I speak this to your shame." (1 Cor 15:34)
"For he hath made him to be sin for us, who knew no sin; that we might be made the righteousness of God in him." (2 Cor 5:21)
"Finally, brethren, farewell. Be perfect, be of good comfort, be of one mind, live in peace; and the God of love and peace shall be with you." (2 Cor 13:11)
"And you hath he quickened, who were dead in trespasses and sins;
Wherein in time past ye walked according to the course of this world, according to the prince of the power of the air, the spirit that now worketh in the children of disobedience:
Among whom also we all had our conversation in times past in the lusts of our flesh, fulfilling the desires of the flesh and of the mind; and were by nature the children of wrath, even as others." (Eph 2:1-3)
"Let us therefore, as many as be perfect, be thus minded: and if in anything ye be otherwise minded, God shall reveal even this unto you." (Phil 3:15)
If Paul's teachings aren't enough, I have more from Peter and John.
While perfect obedience in the OT was not yet possible, since the resurrection of Christ and rebirth from God's seed it is possible
You have Paul's teachings above.
Here are Peter's...
"But as he which hath called you is holy, so be ye holy in all manner of conversation;
Because it is written, Be ye holy; for I am holy." (1 Peter 1:15-16)
"Forasmuch then as Christ hath suffered for us in the flesh, arm yourselves likewise with the same mind: for he that hath suffered in the flesh hath ceased from sin;" (1 Peter 4:1)
"According as his divine power hath given unto us all things that pertain unto life and godliness, through the knowledge of him that hath called us to glory and virtue:
Whereby are given unto us exceeding great and precious promises: that by these ye might be partakers of the divine nature, having escaped the corruption that is in the world through lust." (2 Peter 1:3-4)
“Wherefore the rather, brethren, give diligence to make your calling and election sure: for if ye do these things, ye shall never fall:" (2 Peter 1:10)
"Wherefore, beloved, seeing that ye look for such things, be diligent that ye may be found of him in peace, without spot, and blameless." (2 Peter 3:14)
I still have John's to go.
Those are called temptations, and even Jesus had them...but since Jesus' resurrection, we have been equipt to resist temptations. (James 4:7)
That verse of 1 John, with verses 6 and 10, address those walking in darkness-sin.
It is the sinners who cannot say they have no sin.
Those who walk in the light-God can say they have no sin, as there is no sin in God. (1 John 1:5)
People who want to call themselves Christians, don't want to keep committing sin.
They could have just converted to Judaism for that.
