1) If a non-muslim ( hindu or christian, etc ) gives money towards the building of a mosque, is it acceptable?
2) If the whole project of building a mosque has been financed by a non-muslim, can we pray in such a mosque? Will our prayers be acceptable?
3) If a non-muslim has financed the building of a madrasah, or some classes of that madrasah, is that acceptable? Can our children learn there?
1. It can be accepted if he does not expect anything in return and he is doing it only for reward, nor do you feel afraid that he may use this as a marketing tool.
2. As above.
3. As above.
And Allah Ta’ala (الله تعالى) knows best.