The Exalted also says:
“Ask those of Our messengers whom We sent before you: Did We ever appoint, apart from the Most Compassionate, any deities to be worshipped?” (al-Zukhruf 43:45).

And He says:
“We certainly sent to every nation a messenger, [proclaiming]: ‘Worship Allah and shun false gods.’ Among them were those whom Allah guided, and among them were those for whom misguidance was decreed.” (al-Naḥl 16:36).

Thus, “children of al-ʿallāt” are siblings who share one father while their mothers differ. The father here represents the religion—tawḥīd—whereas the mothers correspond to the diverse religious laws whose rulings vary, as the Most High says:
“For each of you We have appointed a law and a clear way.” (al-Māʾidah 5:48)

He also says:
“For every nation We have appointed a rite which they observe.” (al-Ḥajj 22:67)

And He says:
“To each there is a direction to which he turns.” (al-Baqarah 2:148), according to one of the two interpretations of the verse (1).

The point is that although the revealed codes of law differed over time, all of them commanded the worship of Allah alone with no partner. That is the religion of Islam which Allah prescribed for all the prophets, and it is the only religion Allah will accept on the Day of Resurrection, as He says:
“Whoever seeks a religion other than Islam, it will never be accepted from him, and in the Hereafter he will be among the losers.” (Āl ʿImrān 3:85).

He also says:
“Who would turn away from the way of Abraham except one who debases himself? We chose him in this world, and in the Hereafter he will surely be among the righteous. When his Lord said to him, ‘Submit,’ he said, ‘I submit to the Lord of all worlds.’ Abraham enjoined this upon his children, and so did Jacob: ‘My sons, Allah has chosen the faith for you, so do not die except in a state of Islam.’” (al-Baqarah 2:130-132).

And He says:
“Indeed, We sent down the Torah containing guidance and light. The prophets who had submitted judged by it for the Jews…” (al-Māʾidah 5:44).

Hence, the essence of Islam is to worship Allah alone with no partner, devoting all acts of worship sincerely to Him, and to perfect that worship in the manner prescribed at the time. For this reason Allah will not accept any deed from anyone after He sent Muḥammad ﷺ unless (2) it is in accordance with what He legislated, as He says:
“Say, O people, I am the Messenger of Allah to you all.” (al-Aʿrāf 7:158).

He also says:
“This Qur’an has been revealed to me so that I may warn you with it, and whomever it reaches.” (al-Anʿām 6:19).

And He says:
“Whoever from the factions disbelieves in it—the Fire will be his promised abode.” (Hūd 11:17).

The Messenger of Allah ﷺ said:
“I have been sent to the red and the black,”
meaning, it is said, the Arabs and the non-Arabs, and it is also said: mankind and the jinn (3).

He ﷺ also said:
“By Him in Whose hand is my soul, were Moses to appear among you and you were to follow him, leaving me, you would surely go astray.” (4) There are very many narrations to this effect.

In sum, “half-brothers through the father (ikhwat al-ʿallāt)” are those who share one father but have different mothers—so named from drinking al-ʿalal after al-nahal—whereas “half-brothers through the mother (ikhwat al-akhyāf)” are the opposite: they share one mother but have different fathers. “Full brothers (ikhwat al-aʿyān)” share both father and mother. And Allah knows best.