The biggest concern, I believe, is related to freedoms lost. For instance, the church being sued for 'equal access' of their building, is a clear infringement on the free exercise of religion. Indiana was told it has no right, as a state, to make its own law to protect this religious freedom.
If I don't have a right to protect my family from other's values, I don't have a right to homeschool any longer either. The slope is slippery and we are seeing an assault on our values and our rights, as Christians. Society will not tolerate bigotry, and in so doing, is bigoted itself, but that pendulum swing will cause a lot of damage as the massive wrecking ball that it is.
It will and does undermine biological families. It does and will continue to assault religious value. I don't hate gays, but I do want to protect my family from the onslaught and assault. The national assault against Indiana is an assault on a necessity: We HAVE to be in the world, but not of it, and have nothing to do with them. Ephesians 5:11
Thus, a restriction on a Christian's ability to buy and sale is the mark of the beast. Christians will not be able to buy and sale, if they are to follow these teachings. So far, it is just about 'sell.'
The issues then, are much larger than the context of an unbeliever's sin. We have never been assaulted by polygamists, adulters, or other practicing sinners to accept their sin as normal nor a demand that we not see it as sin. I can refuse a drunk. I can't refuse a homosexual? If I can't refuse ANYBODY, to protect my family, my values, or my business, I've lost significant rights, in favor of the offender.