What is the ruling on a Muslim entering a church to listen to a lecture delivered there?

Scholars have differed on the ruling regarding entering churches. The Hanafis and Shafi'is (with the Shafi'is stipulating the presence of images) went with prohibition (tahrim), while the Hanbalis opted for dislike (karahah), especially if they contained images. Some Hanbalis and Ibn Hazm held the view of absolute permissibility.

The evidence for prohibition and dislike includes prophetic hadiths that forbid entering places with images, and the action of Umar ibn al-Khattab (may Allah be pleased with him).

The evidence for permissibility includes Umar's conditions on the People of the Book and the conduct of Ali ibn Abi Talib (may Allah be pleased with him).

In conclusion: There is no explicit evidence for the prohibition of entering churches, but it is disliked to enter without need. It may reach the level of prohibition if it leads to harm, such as affirming the polytheism of Christians or showing affection towards them. It is permissible for the purpose of inviting to Islam, provided that one does not participate in their worship or become influenced by their beliefs.