The ruling on the fasting of a People of the Book member who has not embraced Islam

This is the first message in the program, received from listener Shihata Abdul-Fadil, an Egyptian national residing in the city of Riyadh. He says: There is a Christian man in our village who fasts the month of Ramadan but does not pray. Is his fasting valid? Please inform us, may Allah reward you.
Answer: In the name of Allah, the Most Gracious, the Most Merciful. Praise be to Allah, Lord of the worlds, and the final outcome is for the righteous. And may Allah send prayers and blessings upon His servant and messenger, His choice from among His creation, and His trustee over His revelation, our Prophet and our Imam Muhammad ibn Abdullah, and upon his family and his Companions, and whoever follows his path and is guided by his guidance until the Day of Judgment.
As for what follows: This Christian who fasts but does not pray must be looked into, and he must be called to Islam. For fasting without entering into Islam does not benefit him, as disbelief invalidates deeds, as He said: : [Al-Ma'idah:5], and He said: [Al-An'am:88]. Therefore, first, he must believe in the Prophet Muhammad (peace and blessings be upon him) and enter into Islam. Once he believes in Muhammad (peace and blessings be upon him) and enters into Islam, he is then required to perform prayer, fasting, zakah, Hajj, and other obligations. As for his fasting or praying while he remains a Christian, this is not valid from him; his prayer is invalid and his fast is invalid, and it does not benefit him, because the condition for these acts of worship is Islam. If he prays while he is not a Muslim, or fasts while he is not a Muslim, his acts of worship are invalid.
So, you brothers who are near him, you must advise him and direct him to Islam, and teach him that it is obligatory to believe in Muhammad (peace and blessings be upon him) and confirm that he is the Messenger of Allah in truth to all people, both jinn and humans. He must commit to Islam by being sincere in worship to Allah alone and abandoning what the Christians hold regarding the claim that the Messiah is the son of Allah or the Trinity. He must abandon all of this and believe that Allah is one God with no partner, and that the Messiah, son of Maryam, is a servant of Allah and His messenger, and not the son of Allah. Exalted is Allah in great exaltation. For Allah, Glorified and Exalted is He, has no wife and no son. He said: : [Al-Ikhlas:1-4]. If he abandons this ugly claim held by the Christians, and if he believes in Muhammad (peace and blessings be upon him), confirms what he brought, and commits to Islam, then he is a Muslim at that time. He has what Muslims have, and he is obligated with what Muslims are obligated with. He must pray, he must fast, he must pay zakah if he has wealth, and he must perform Hajj if he is able, just like the other Muslims. Yes.