A group of people get together and decide that they share a belief. In this case, it is a religious belief. They believe that homosexuality is a sin and that supporting it is wrong. A member of their congregation openly takes action to support same-sex benefits directly in opposition to their previously shared beliefs. The question here is whether or not this group has the right to decide the beliefs of it's group.
Suppose this member now decides that Jesus Christ is NOT the son of God and never even existed? In public, this member actively supports an activity that reflects that new belief. And is this group then supposed to be 'tolerant' of this new belief of one member. Suppose it involves incest, or rape, or the fact that Adolf Hitler was just a misunderstood momma's boy and the holocaust was a lie?
Christianity loves the sinner but hates the sin. If homosexuality is a sin to this church group, then being tolerant of a member that supports the activity is hypocritical at best. If the member now supports the activity, after knowing all along that the group does not and will not, then I believe that the member is incredibly self-centered if they foolishly believe that the group should change their views to accomodate the single member.
I see on this forum all the time people that attempt to quote repeatedly that 'Christians should not judge other people.' What a load of crap and nothing is further from the tenets of Christianity. A single passage of the bible, taken out of context, does not relinquish people from the fact that we are called by Christ to see the evil in the world for exactly what it is and to refrain from it. My friends, THAT by its very definition is judging. To this group, homosexuality is a sin. They are called to see it for what it is and to refrain from it. By allowing a member to support it is in itself a tacit approval of the sin. As a Christian, the type of Christian that I believe we should be, we MUST see activities for what they are and then judge if they are sinful or not. Letting everybody do their own thing is a saying on a poster from the 60's, NOT a tenet of Christianity.
If the member changes their belief then the reasonable expectation is that the member should join a congregation that does not believe that homsexuality is a sin. To believe, even for an instant, that the Church your family has attended for 60 years is going to change just because you want it to is ridiculous and idiotic. I believe there are a number of Unification churches that even accept gay clergy. They should go there.