What's sad is I've talked to professing Christians who don't see anything wrong with gays adopting or homosexual marriage. When I point them to the Bible and what God says, they kinda shake their head, shrug their shoulders and ignore it. But you're right, many Bible believing, church going Christians do not approve, and rightly so.
Every Christian is accountable for knowing the Truth of God's Word. And if we know something is wrong and do nothing about it....that is counted as sin.
I believe that this issue is a defining moment for American churches. The question is, will Christians make a stand for Truth?