As christians should we not be trying to help our nonchristian fellows to live a life that causes less harm? Which would include not living in a gay marriage.
By accepting gay marriage are you not accepting that it is ok for them to have homosexual relations which the Bible explicitly says it is not ok?
By saying gay marriage is ok your normalise behaviour that shouldnt be normalised. By normalising it, you lead more people into sin, as social acceptance of homosexual acts which is evil will thus increase.
Yes we need to be Christian in the way we go about it, but it does not mean we have to change our beliefs or lessen the seriousness of the sin. People who feel homosexual urges should be welcomed into the Church, but they need to know that to commit a homosexual act is a sin. We all have urges such as my sexual urges. But I do my best to avoid committing a sin where i would have sexual relations outside marrirage.