First you need to realize that there are 2 kinds of lgbtq; Side A, and Side B - There's no real sin with Side B like there is Side A.

With Side B homosexuality is just an identity meaning; they believe it's okay to be a homosexual as long as you remain celibate since you can't choose your sexual preferences, but you can choose what you do with them. Whereas to Side A homosexuality is more than an identity; meaning they believe that there is no sin with being a homosexual, and having homosexual sex.

Thankfully there is forgiveness though, but I do think this can only happen if Side A admits that homosexuality IS a sin. Not saying they have to turn from their sins to be Saved, because we are NOT Saved by our works, but by our Faith in Jesus Christ. But I believe that if someone claims they have no sin / don't sin then they can't have true repentance, which is admitting you are a sinner in need of a Saviour.

Even though I do not believe sin effects our Salvation (since sin is something we all do), I still absolutely believe it bares consequences in our lives.

I honestly think a lot of it boils down to a heart thing, God sees the heart where we see the outward appearances. If someone is truly being convicted and struggling with their homosexuality (having gay sex) even if they never change I believe that's a sign they are Saved, but if someone is not being convicted and they are accepting of that lifestyle along with claiming it's not sinful then I do doubt their initial conversion.

But to answer your question should Christianity support the lgbtq?; Side B why not? but Side A absolutely NOT. Even though I believe in Once Saved - Always Saved, I still do think people that are having gay sex need to know just how their lives can be impacted by that. They need to be warned that participating in the Pride Parades supporting those things is not good and God detests it, especially with people running around with nothing but pasties on in front of innocent children (I will never support those things). They need to realize that the lifestyle they are living has repercussions, it's no secret that most homosexuals are not monogamous which opens the individual up to stds, hiv, and even aids. On top of that continual anal sex has it's own issues, from fissures, to hemorrhoids, to anal gapes, and anal leakage. Of course many will say those claims are false, but I absolutely don't believe that in fact I have read stories about people who came out of that lifestyle, but they unfortunately suffered issues with their bottoms after that.

Anyway, there's hope in Christ - we just have to want it.