Explanation of the author's statement: "…if he prays, he is a Muslim by ruling…"

The Shaykh : He said, "If he prays, he is a Muslim by ruling". If he prays, who is it? The disbeliever. He is a Muslim by ruling, meaning that we rule that he is a Muslim. If a disbeliever stands up and prays—saying the takbir, opening the prayer, reciting, bowing, prostrating, and saying the taslim—you would say he is a Muslim. But is he a Muslim in reality, or a Muslim by ruling? By ruling. Even if he did not intend Islam, by what he did, he is a Muslim. A Muslim by ruling means according to our ruling concerning him in this world. The benefit of this is that if we rule that he is a Muslim, we demand of him the obligations of Islam.