What is the ruling on believing in the unity of religions and advocating for it, and what are the implications of that, such as the acceptance of all deeds, the inevitability of entering Paradise, the permissibility of intermarriage, and the illegitimacy of killing an apostate?

If the speaker means, by saying that the heavenly religions are one and the same, that the religion of the prophets is Islam, which is based on the Oneness of God (Tawhid), then this is true. However, if they mean that Islam and the distorted religions (such as Judaism and Christianity) are all one religion and from God, then this is clear misguidance and contrary to the Qur’an and reason, because the religion of Tawhid cannot be the same as the religion of the Trinity.

The statement that a non-Muslim will enter Paradise is misguidance and contradicts the Qur’an, the Sunnah, and the consensus of the Ummah; based on the saying of the Prophet, peace be upon him: "Indeed, none shall enter Paradise except a Muslim soul."

The permissibility of a Muslim man marrying a woman from the People of the Book is not because her religion is true or that she will enter Paradise, but rather for the wisdom hoped for from her inclination towards Islam. The killing of an apostate from Islam, even if they convert to Judaism or Christianity, is established by authentic hadiths and the consensus of scholars.

These false beliefs often result from the weakness of Muslims, their lack of knowledge, and their being influenced by the prevailing power of disbelief and its people in our time.