What is the ruling on Muslims entering churches, temples, and other houses of worship belonging to non-Muslims, and is it permissible to cite the action of Umar ibn al-Khattab, may Allah be pleased with him, when he entered one of the churches of the people of Jerusalem, as evidence for this?

It is not permissible to enter churches if there is an objectionable matter (munkar) within them, but it is permissible if there is none. Statements have been transmitted from scholars, some of which include: absolute dislike of entering them, or permissibility without dislike, or permissibility as long as there are no images within them. Others hold the view that it is permissible to enter them and pray therein if they are clean. It has been narrated that Umar (may Allah be pleased with him) did not enter the church in Jerusalem due to the presence of images within it.