He is the supreme authority. Why does he need to ‘curse’ his own creations?
Quran 9:30 “the Jews call ‘Uzair a son of Allah, and the Christians call Christ the son of Allah. …they but imitate what the unbelievers of old used to say. Allah’s curse be on them: how they are deluded away from the truth!”
Quran 3:56 “As for those who reject faith [Jews, Christians, pagans and atheists] , I will punish them with a terrible agony in this world and the next. They have no one to help or save them.”
From an outsider’s perspective as an ex-Christian who has studied human relationships, I can see that the verses quoted above serve to unite Islam against Jews and Christians. That, I would say, is one goal of most religions: to unite “insiders” against “outsiders.”
Obviously, it is a fearsome verse for those of us who are outside Islam because we tend to be afraid that Muslim terrorists will use it to justify acts of violence against us. However, picking out single verses from Holy Texts is called cherry picking. If one cherry-picks the Christian Bible, or Buddhist Holy Books, or the Holy Books or Oracles of any belief system, I am sure one can find equally terrifying lines. Here are some quotes from the KVJ of the Christian Bible.
6 Thy right hand, O Lord, is become glorious in power: thy right hand, O Lord, hath dashed in pieces the enemy.
9 Behold, the day of the Lord cometh, cruel both with wrath and fierce anger, to lay the land desolate: and he shall destroy the sinners thereof out of it.
10 For the stars of heaven and the constellations thereof shall not give their light: the sun shall be darkened in his going forth, and the moon shall not cause her light to shine.
11 And I will punish the world for their evil, and the wicked for their iniquity; and I will cause the arrogancy of the proud to cease, and will lay low the haughtiness of the terrible.
15 Every one that is found shall be thrust through; and every one that is joined unto them shall fall by the sword.
16 Their children also shall be dashed to pieces before their eyes; their houses shall be spoiled, and their wives ravished.
10 The same shall drink of the wine of the wrath of God, which is poured out without mixture into the cup of his indignation; and he shall be tormented with fire and brimstone in the presence of the holy angels, and in the presence of the Lamb
8 But the fearful, and unbelieving, and the abominable, and murderers, and whoremongers, and sorcerers, and idolaters, and all liars, shall have their part in the lake which burneth with fire and brimstone: which is the second death.
These are but a few of the biblical verses that savagely condemn “outsiders,” i.e. people who are not the chosen or saved People of God, True Believers.