Surah 2. Al-Baqara, Ayah 114

It is one of the fundamental principles of Islam that every religion which has belief in God as its focal point must be accorded full respect, however much one may disagree with its particular tenets. Thus, the Muslims are under an obligation to honour and protect any house of worship dedicated to God, whether it be a mosque or a church or a synagogue (cf. the second paragraph of 22:40 ); and any attempt to prevent the followers of another faith from worshipping God according to their own rites is condemned by the Qur'an as a sacrilege. A striking illustration of this principle is forthcoming from the Prophet's treatment of the deputation from Christian Najran in the year 10 H. They were given free access to the Prophet's mosque, and with his full consent celebrated their religious rites there, although their adoration of Jesus as "the son of God" and of Mary as "the mother of God" was fundamentally at variance with Islamic beliefs (see Ibn Sa'd I/1, 84 f.).

 Or “Such people should not have even entered these places except with reverence.”

There were actually Pagans in Mecca who tried to shut out the Muslim Arabs from the Ka'ba, the universal place of Arab worship. The Pagans themselves called it the House of God. With what face could they exclude the Muslims, who wanted to worship the true God instead of worshipping idols? If these Pagans had succeeded, they would only have caused violent divisions among the Arabs and destroyed the sanctity and the very existence of the Ka'ba.