Answer

Asalaamualaykum, I wanted to know is it haram for a Muslim to enter a church?

Answer:

Wa alaykum salam wa rahmatuLlahi wa barakatuHu,

If there are no venerated statues or images of living things on walls, windows,  or ceilings, then one may enter the church if he has permission from a Christian.  However,  If there are statues or images present on walls,  windows, or ceilings, then it is not permitted for a Muslim to enter, even with their permission.

Tuhfat-al-Muhtaj v9p295
Mughni-al-Muhtaj v6p78

Answered by: Shaykh Omar Mohsin