The only qualification we suggest is that mentees profess to have a relationship with Jesus. If you have a guy in your group who is not a follower of Jesus, he will quickly turn into the group project of the group. The intent of mentoring groups is to go deep, focusing on practical, actionable takeaways. So, you want all the guys to be starting from a roughly similar belief system. Otherwise, it’s easy to get lost down a theological rabbit hole. But besides that, it’s perfectly ok to have men of varying levels of faith; in fact, it could even be beneficial.