Will the fast of one who collects donations for the church during Ramadan be accepted?

Building or supporting churches is a grave evil, because it aids in the spread of disbelief (kufr). Whoever believes that churches are houses of God, or that God is worshipped therein, or that what Christians do is worship, is a disbeliever. It is not permissible for a Muslim to build a church or a place of worship that is not founded upon Islam. Those who do so must be reminded to repent.