Is it permissible to emigrate with a Muslim child to a Muslim country without the permission of his unbelieving father?

The mother's custody is forfeited if her husband consummates the marriage with her, and custody transfers to another guardian according to the order of custodians. If there is no guardian prioritized over the father, custody transfers to him. However, the father's transgression (fisq) forfeits his right to custody, for there is no custody for a transgressor who does not protect the child. The guiding principle is the child's best interest. If his transgression is proven, the mother must appeal to a Muslim judge or to Islamic centers in the West to reclaim the child from him.