The Conditional Promise
Allaah (The Most High) stated:
وَعَدَ اللَّهُ الَّذِينَ آمَنُوا مِنكُمْ وَعَمِلُوا الصَّالِحَاتِ لَيَسْتَخْلِفَنَّهُم فِي الْأَرْضِ كَمَا اسْتَخْلَفَ الَّذِينَ مِن قَبْلِهِمْ وَلَيُمَكِّنَنَّ لَهُمْ دِينَهُمُ الَّذِي ارْتَضَى لَهُمْ وَلَيُبَدِّلَنَّهُم مِّن بَعْدِ خَوْفِهِمْ أَمْنًا يَعْبُدُونَنِي لَا يُشْرِكُونَ بِي شَيْئًا وَمَن كَفَرَ بَعْدَ ذَلِكَ فَأُوْلَئِكَ هُمُ الْفَاسِقُونَ
Allah has promised those among you who believe, and do righteous good deeds, that He will certainly grant them succession to (the present rulers) in the earth, as He granted it to those before them, and that He will grant them the authority to practise their religion, that which He has chosen for them (i.e. Islam). And He will surely give them in exchange a safe security after their fear (provided) they (believers) worship Me and do not associate anything (in worship) with Me. But whoever disbelieved after this, they are the Fasiqun (rebellious, disobedient to Allah).