The messengers were sent by Allāh to teach mankind how to worship in a manner that is pleasing to Him!

Tawḥīd is the greatest of what Allāh commanded with, because it is the foundation upon which the whole religion is built.

al-ʿAllāmah Muḥammad bin Ṣāliḥ al-ʿUthaymīn (رحمه الله) clarifies the correct meaning of the Shahādah. Contrary to the false widespread definition, the Shahādah does not mean “there is no god but God“.