sincere faith and belief

إِنَّهُۥ كَانَ فَرِيقٌ مِّنْ عِبَادِى يَقُولُونَ رَبَّنَآ ءَامَنَّا فَٱغْفِرْ لَنَا وَٱرْحَمْنَا وَأَنتَ خَيْرُ ٱلرَّٰحِمِينَ

Indeed, there was a party of My servants who said, 'Our Lord, we have believed, so forgive us and have mercy upon us, and You are the best of the merciful.'