Catholic canon law requires that a marriage be between two people who are free to marry. A divorced Muslim is generally not considered free to marry in the Catholic Church unless their prior marriage has been declared null by a competent tribunal (typically a religious court of their own faith).
Even if the Muslim's prior marriage has been declared null, there are other considerations:
* Disparity of Cult: Catholic canon law requires a dispensation from the local bishop for a Catholic to marry a non-baptized person. This is called a "disparity of cult" dispensation. It is typically granted if the Catholic party promises to do all in their power to have the children baptized and raised in the Catholic faith, and the non-Catholic party is informed of this promise.
* Canonical Form: Catholic marriages are usually required to take place in a Catholic church with the authorization of a priest or deacon. A dispensation from canonical form may be granted in certain circumstances, allowing the marriage to take place elsewhere.
In summary, a divorced Muslim can potentially marry a single Catholic in the Catholic Church, but it is a complex process that requires:
1. Proof of Nullity: The Muslim's previous marriage must be declared null by a competent tribunal.
2. Dispensations: The Catholic party will likely need a dispensation from the local bishop for disparity of cult and possibly for canonical form.
3. Commitment to Catholic Upbringing: The Catholic party must promise to do all in their power to raise their children in the Catholic faith.
It is essential for the Catholic party to speak with a Catholic priest to discuss their situation and receive guidance on the necessary steps.