Quran 18:20

إِنَّہُمۡ إِن يَظۡهَرُواْ عَلَيۡكُمۡ يَرۡجُمُوكُمۡ أَوۡ يُعِيدُوڪُمۡ فِى مِلَّتِهِمۡ وَلَن تُفۡلِحُوٓاْ إِذًا أَبَدً۬ا ٢٠

"If they discover you, they will stone you, or force you to revert to their religion, then you can never succeed."