I have a friend whos children were placed with a church family in Ft. Myers, Fl. without his knowledge how can he get them back?

He absolutely has the right to recover his children. If the children were born during the marriage, he is the legal father and is entitled to custody of his children, unless there is a court order in place. Ordinarily, if the children are in the custody of third parties, he can simply go and pick them up. His first step should be to locate the children and attempt to pick them up. If they do not willingly turn over his children, then he should seek assistance from law enforcement. If he hasn't done so already, he should consider filing a dissolution of marriage and get a temporary order for timesharing so he can get children, even if the mother were to regain custody.

Communicate with the church that he'd like to know where the children are placed and have them returned. If that doesn't work, call the police; it's fairly considered kidnapping if nothing has been filed with the courts.