Most Protestant denominations use the term minister to describe their clergy, but it is not a formal title and is not capitalized. It is also used in Catholicism, with a strong distinction drawn between ordained ministers (priests and deacons) and lay ministers (including, for example, Eucharistic ministers, who take Communion to the sick, and youth ministers). The Nation of Islam also uses the term, and in that case it is a title and should be capitalized before the person’s name.
REFERENCE: Religion Stylebook