—indeed, impossible in the judgment of Muslims—that he, peace be upon him, should neglect to explain to people something without which no one’s Islam is valid, and that all Muslims should then agree to overlook it or deliberately leave it unmentioned, only for these wretched men to explain it. Whoever thinks that he has grasped something of religion that the Messenger of Allah, peace and blessings be upon him, did not grasp is an unbeliever, without disagreement.

Thus, it is established that this doctrine violates the consensus and opposes Allah, His Messenger, and all Muslims without exception).

[Ibn Taymiyyah’s Commentary]

I say:

Accepting a person’s outward profession of Islam entails applying the outward legal rulings of Islam to that person, such as the inviolability of life and property, marriage, inheritance, and the like.

For this, an outward declaration alone suffices, even if what is within the person remains unknown.

As he, peace and blessings be upon him, said:

“Once they say it, their lives and property are protected from me, except as its rightful requirements demand, and their reckoning is with Allah.”

He also said:

“I have not been commanded to probe people’s hearts or to cut open their bellies.”