Surah Ash-Shura, ayah 8

وَلَوۡ شَآءَ ٱللَّهُ لَجَعَلَهُمۡ أُمَّةٗ وَٰحِدَةٗ وَلَٰكِن يُدۡخِلُ مَن يَشَآءُ فِي رَحۡمَتِهِۦۚ وَٱلظَّٰلِمُونَ مَا لَهُم مِّن وَلِيّٖ وَلَا نَصِيرٍ ٨

Walaw shā'allāhu laja'alahum ummatan wāhidatan walākin yudkhilu man yashā'u fī rahmatihī waz-zālimūna mā lahum min waliyyin walā nasīr

And if Allāh willed, He could have made them [of] one religion, but He admits whom He wills¹⁴⁰⁹ into His mercy. And the wrongdoers have not any protector or helper.