Quran 2:120 Al-Baqarah, ayah 120 of 286

وَلَن تَرْضَىٰ عَنكَ ٱلْيَهُودُ وَلَا ٱلنَّصَـٰرَىٰ حَتَّىٰ تَتَّبِعَ مِلَّتَهُمْ ۗ قُلْ إِنَّ هُدَى ٱللَّهِ هُوَ ٱلْهُدَىٰ ۗ وَلَئِنِ ٱتَّبَعْتَ أَهْوَآءَهُم بَعْدَ ٱلَّذِى جَآءَكَ مِنَ ٱلْعِلْمِ ۙ مَا لَكَ مِنَ ٱللَّهِ مِن وَلِىٍّ وَلَا نَصِيرٍ ۝١٢٠

2:120 And the Jews will not be pleased with thee, nor will the Christians, till thou follow their creed. Say: Lo! the guidance of Allah (Himself) is Guidance. And if thou shouldst follow their desires after the knowledge which hath come unto thee, then wouldst thou have from Allah no protecting guardian nor helper.