Overall meaning :
Allah, Exalted be He, points out one aspect of His absolute power. He says: It is He who shows you lightning, as one of His signs, inspiring in you both fear of thunderbolts and hopeful expectation of rain, and by His utter power produces rain-laden clouds for your own benefit. The thunder declares His glory and perfection in total submission to Him, and so do the angels in great fear and awe of Him. He sends destructive thunderbolts, striking with them whomever He wills of His creatures. Yet, the unbelievers stubbornly argue about Allah’s unity and power to resurrect the dead despite all evidence that He is tremendous in might and severely punishes those who disobey Him.
The call of truth—true worship—belongs to Him alone, for none is deserving of worship except He, but the deities that the idolaters worship and call upon besides Allah can never respond to them in any way. Those who worship them are like a thirsty person who stretches out his hands to water, signalling to it and asking it to come to his mouth, but it will never come. The unbelievers’ prayers to such false deities are only in vain.