Quran 4, An-Nisa (the Women) ⓘ

4:136O ye who believe! Believe in Allah and His messenger and the Scripture which He hath revealed unto His messenger, and the Scripture which He revealed aforetime. Whoso disbelieveth in Allah and His angels and His scriptures and His messengers and the Last Day, he verily hath wandered far astray.

يَا أَيُّهَا الَّذِينَ آمَنُوا آمِنُوا بِاللَّهِ وَرَسُولِهِ وَالْكِتَابِ الَّذِي نَزَّلَ عَلَى رَسُولِهِ وَالْكِتَابِ الَّذِي أَنْزَلَ مِنْ قَبْلُ وَمَنْ يَكْفُرْ بِاللَّهِ وَمَلَائِكَتِهِ وَكُتُبِهِ وَرُسُلِهِ وَالْيَوْمِ الْآخِرِ فَقَدْ ضَلَّ ضَلَالًا بَعِيدًا

4:137Lo! those who believe, then disbelieve and then (again) believe, then disbelieve, and then increase in disbelief, Allah will never pardon them, nor will He guide them unto a way.

إِنَّ الَّذِينَ آمَنُوا ثُمَّ كَفَرُوا ثُمَّ آمَنُوا ثُمَّ كَفَرُوا ثُمَّ ازْدَادُوا كُفْرًا لَمْ يَكُنِ اللَّهُ لِيَغْفِرَ لَهُمْ وَلَا لِيَهْدِيَهُمْ سَبِيلًا