Overall meaning :
After mentioning His praise for the believers, Allah Almighty proceeds to show the clear signs and indications of faith and to establish monotheism through the greatest and the most conclusive means of adopting it, namely His own testimony. He himself bears witness that there is no god worthy of worship except He, and so do His angels and those of His servants endowed with knowledge. He executes justice under all circumstances, and all His actions are characterised by absolute justice.
Then He stresses His sole prerogative to be worshipped alone—being the only one rightly deserving of worship, stating that He is the All-Strong, the possessor of the ultimate strength and ability whose plans no one can possibly frustrate; and the All-Wise, whose statements and actions are characterised by perfect wisdom.