When you look at the types of faith people have, you can't simply take on part or the parts you like/dislike from it to make it look good/bad.
Adam sinned, pure and simple. Did God know it was going to happen. Yes, did Adam know that God knew it was going to happen. NO. Did Adam talk to God(pray) before he did it? No. So, there you have it. Adam used his own free will to sin just like we all can.
So, when you look at homosexuality. God calls it a sin. Just like stealing, fornication, adultery, lying, murder they are all sin. We have the choice within the realm of the bible. It is sin. I didn't say that. That's thus saith the Lord. So please don't say "it's not sin", because it is. Now if you want to disassociate yourself entirely from God and say that then that's fine.
Is love sinful.? Yep, it's sinful.

John 3:16 "For God so loved the world, that he gave his only begotten Son, that whosoever believeth in him should not perish, but have everlasting life." So Love is not sinful in the slightest. Expressions of lust can be very sinful.