وَمَا لَكُمْ لَا تُؤْمِنُونَ بِاللَّهِ وَالرَّسُولُ يَدْعُوكُمْ لِتُؤْمِنُوا بِرَبِّكُمْ وَقَدْ أَخَذَ مِيثَاقَكُمْ إِن كُنتُم مُّؤْمِنِينَ
Why should you not have faith in Allah when the Apostle invites you to have faith in your Lord, and He has certainly made a covenant with you, if you are [genuinely] faithful?
Agha Ali Puya Commentary
Commentary on Quran 57:8
[Pooya/Ali Commentary 57:8] In the light of what has been stated in verses 1 to 6 every man must believe in Allah particularly when He has sent the Holy Prophet with the verses of the Quran and his life pattern (sunnah) in which Allah's plan and purpose were unfolded, to guide man to the right path. Some commentators say that the covenant refers to the promise taken by Allah from every soul in the spiritual realm that it would serve and worship Him alone. There is also the implied covenant that he who accepts the invitation of the Holy Prophet to believe in the gospel of unity will believe in Allah and serve Him and His servants.