Because...
1 Jn 3:8 (NET)
The one who practices sin is of the devil, because the devil has been sinning from the beginning. For this purpose the Son of God was revealed: to destroy the works of the devil.
If one practices a sin, such as homosexuality, and after hearing the truth continues to practice it, they have given themselves over to the devil. They are of the devil according to scripture.
I've read this in the Logos and it told me what God has to say on the matter. I prayed about it and the Holy Spirit gave me Rhema about it, understanding that the homosexual having heard the Word and continuing in their sin is of the devil.