As Christians it's not our job to judge the unsaved. But to love them and at least warn them of the truth. We would welcome a gay person into our church.
However, and this is something a lot of churches miss, according to the Bible we are not to accept a Christian just happily living in sin with no attempt to change. If we notice another Christian has sin that they are not dealing with we are to go to them and talk to them about it. But if no matter who talks to them about it and they are not willing to change even though it can be clearly seen in scripture they are in sin then we are not to associate with them.
This is probably so they don't teach others their ways and so they don't give Christianity a bad name by professing the faith then not living it out.
But again, being gay is not a sin, it's not something you can help. Although I do believe God can transform people if they are willing. It's the lifestyle.
It's one of many sins, and they should ALL be treated the same (by the church, obviously the law has to take action with sins some sins that affect others).
And of course everyone sins, but Christians are not to just happily allow it to be a normal part of their lives.
PS When I say "sin" I'm saying all this according to the Bible and my religion. And of course I would expect my church to believe the same about that.