I believe God does call people to hold convictions in certain areas that aren't necessarily commands of Scripture. They need to follow that. But when convictions become someone's law and they start to look down on or gossip about those who don't hold those same convictions I think it's wrong.
Many believe God has called them to certain convictions and then try to back it with Scripture often taking it out of context or making a Scripture verse into a command when it isn't. If God calls you to a conviction you don't need to try to justify it with Scripture!
I was reading about the Rechabites and their father who had a conviction. (Jer. 35) The children chose to follow it. I don't think God is calling everyone to completely abstain from wine (though you shouldn't be getting drunk!) or live only in tents. But this is what one father believed. I think the Rechabites knew this was a father's command and not a command from Scripture. I don't get the impression they tried to twist Scripture to fit their father's conviction. They chose to obey their father's command and God honored them for it.
Many times God will ask us to hold onto a conviction that isn't a command in Scripture. It's okay. We should follow it, but we need to remember its a personal conviction and nothing more. People shouldn't look down on us for having them and we shouldn't feel the need to justify it with Scriptures that aren't there. On the other hand those who hold convictions shouldn't look down on or gossip about those who don't have those same convictions.
Just something that's been on my mind....