Are the children of a Muslim man, whom he begot with a Christian woman whom he had fornicated with and impregnated, then civilly married before separating from her and repenting, legitimate? And what can he do after his repentance?

What a man begets from a woman through fornication is not attributed to him. As for the children he begot from her after the civil marriage and the presence of her guardian, they are his children and are attributed to him, and he must provide for them, even though his marriage is not religiously valid, due to his belief in the validity of the contract.

He must repent from fornication and from his marriage to this fornicating woman, because Allah has only permitted a Muslim to marry a chaste, virtuous woman from the People of the Book, with preference given to marrying a Muslim woman.

After repentance, he must take his children in to raise them according to Islam, and he must choose a Muslim wife who possesses religiosity and good character.