They have to go the extra step and denounce Islam, not just say they don't follow Islam that seriously.
I had several 'Turkish' colleagues in business school, and they all said they were not very religious, but the more I got to know them, the more I found out they were exactly like every other Muslim. They hate the west, they hate America, and they dispise Israel.
At the time, I didnt care, but NOW I look back and am sickened by them.
Islam is like Naziism. yes, there may have been some Germans who grew up in Nazi Germany who didnt take Hitler seriously, and who never read Mein Kampf, but unless they denounce the idiology altogether, I will not associate with them.... EVER!