Catholic Missionaries going to Africa for the salvation of souls is always a winning idea.
These missionaries must be Catholic and must not be syncretists or the people they are trying to bring to Our Lord will think, rightfully if they follow the syncretistic teachings of the post-Vatican II church, that all religions point to God but these novus ordites think they have the best road maps. The missionaries must tell the people flatly and without any beating around the bush, that only the Catholic Faith and Our Lord will lead them to Heaven and will be for the salvation of their souls. They must be taught that all other religions, no matter how enjoyable, are false.
The missionaries must teach that Islam is a false religion and cannot lead to the salvation of their souls.
Then let the people decide. If they do not believe in Our Lord and become Catholic, at least they were warned. Those who do not believe, as Our Lord said, are already condemned.