Read and reflect on verse 21 from Surah Al-Baqara: And when they meet those who have attained to faith, they assert, "We believe [as you believe]"; but when they find themselves alone with their- evil ...
وَإِذَا لَقُوا الَّذِينَ آمَنُوا قَالُوا آمَنَّا وَإِذَا خَلَوْا إِلَىٰ شَيَاطِينِهِمْ قَالُوا إِنَّا مَعَكُمْ إِنَّمَا نَحْنُ مُسْتَهْزِئُونَ
And when they meet those who have attained to faith, they assert, "We believe [as you believe]"; but when they find themselves alone with their- evil impulses, they say, "Verily, we are with you; we were only mocking!"