Why are Mormons and Jehovah's Witnesses considered Christian, but Muslims are not, when they believe the same regarding Jesus, the Trinity, and Bible?

All three believe Jesus is not God, there is no Trinity as understood by traditional Christians, yet at the same time Jesus is the Messiah, the word of God, born of the virgin Mary, and accept the Torah and gospel accounts. Jesus is the Messiah, and word of God (but Trinity is wrong): https://quran.com/4/171?translations=95,101,85,20,18,22,19,17 > O People of the Book! Do not go to extremes regarding your faith; say nothing about Allah except the truth.1 The Messiah, Jesus, son of Mary, was no more than a messenger of Allah and the fulfilment of His Word through Mary and a spirit ˹created by a command˺ from Him.2 So believe in Allah and His messengers and do not say, “Trinity.” Stop!—for your own good. Allah is only One God. Glory be to Him! He is far above having a son! To Him belongs whatever is in the heavens and whatever is on the earth. And Allah is sufficient as a Trustee of Affairs. Jesus fulfills the Torah, and brings the gospel: https://quran.com/en/al-maidah/46 >Then in the footsteps of the prophets, We sent Jesus, son of Mary, confirming the Torah revealed before him. And We gave him the Gospel containing guidance and light and confirming what was revealed in the Torah—a guide and a lesson to the God-fearing. Virgin birth (and immaculate conception?): https://quran.com/en/at-tahrim/12 > ˹There is˺ also ˹the example of˺ Mary, the daughter of ’Imrân, who guarded her chastity, so We breathed into her ˹womb˺ through Our angel ˹Gabriel˺.1 She testified to the words of her Lord and His Scriptures, and was one of the ˹sincerely˺ devout. In the case of Mormons and Jehovah's Witnesses, this is sufficient for them to be considered Christians, but in the case of Muslims, they are considered a foreign religion. What explains this difference in categorization? A corollary, is there a list of minimal beliefs that categorizes a group as Christian or non-Christian, which would categorize Jesus' disciples as Christian? In older times, according to John of Damascus , it seems Islam was considered a Christian heresy, not a separate religion. >From that time to the present a false prophet named Mohammed has appeared in their midst. This man, after having chanced upon the Old and New Testaments and likewise, it seems, having conversed with an Arian monk, devised his own heresy. Based on my limited knowledge of medieval theology, it does seem like Islam (along with Mormonism and Jehovah's Witnesses) would be considered a form of Arianism.