Different denominations have their own unwritten rules of what a Christian should look like. Churches have surrounded themselves with behavioral expectations.
Working together as a group, supporting and loving one another, is not such a terrible thing. But to then judge someone outside the group based on your culture inside the group is such a terrible thing.
So if you are truly an evangelist, you must get very comfortable with the distinction between salvation and lifestyle.
Remember: Jesus came to save the lost... not simply the well dressed, good mannered, generous to a point deacons and elders.