I think this is a starting point.
1Jo 4:15 Whosoever shall confess that Jesus is the Son of God, God dwelleth in him, and he in God.
1Jo 2:23 Whosoever denieth the Son, the same hath not the Father: but he that acknowledgeth the Son hath the Father also.
1Jo 2:22 Who is a liar but he that denieth that Jesus is the Christ? He is antichrist, that denieth the Father and the Son.
1Jo 4:3 And every spirit that confesseth not that Jesus Christ is come in the flesh is not of God: and this is that spirit of antichrist, whereof ye have heard that it should come; and even now already is it in the world.
1Jo 4:5 They are of the world: therefore speak they of the world, and the world heareth them.
1Jo 2:15 Love not the world, neither the things that are in the world. If any man love the world, the love of the Father is not in him.
1Jo 2:16 For all that is in the world, the lust of the flesh, and the lust of the eyes, and the pride of life, is not of the Father, but is of the world.
1Jo 2:17 And the world passeth away, and the lust thereof: but he that doeth the will of God abideth forever.
1Jo 2:19 They went out from us, but they were not of us: for if they had been of us, they would no doubt have continued with us: but they went out, that they might be made manifest that they were not all of us.
I love how Paul, searched out, encouraged, reprimanded, the carnal Corinthians. He didn't give up on them, he prayed for, cried over, and preached to them how to "grow up". He called them brothers. He reminded them of who thery are In Christ Jesus.
1Co 1:5 That in every thing ye are enriched by him, in all utterance, and in all knowledge;
1Co 1:6 Even as the testimony of Christ was confirmed in you:
1Co 1:7 So that ye come behind in no gift; waiting for the coming of our Lord Jesus Christ:
1Co 1:8 Who shall also confirm you unto the end, that ye may be blameless in the day of our Lord Jesus Christ.
1Co 1:30 But of him are ye in Christ Jesus, who of God is made unto us wisdom, and righteousness, and sanctification, and redemption:
But at some point, one needs to be turned over to satan for the destruction of their flesh.
I think the key is, at what point does one need to be cut loose, and turned over to satan for destruction of the flesh??
Somewhere, i can't find it right now; there is a verse re: give them a couple of times to repent, then cut them loose. I think it's in I Timothy??