Overall meaning : Allah Almighty is not ashamed to clarify whatever He wishes by setting forth a parable of any of his creatures, even as small as a gnat or bigger or even smaller. People adopt different stances in this respect according to their beliefs and certainty. The faithful are absolutely certain that the parable is true because it comes from their Lord Himself; as for others, they object to the parables Allah Almighty strikes out.
The reason behind setting forth parables is to distinguish the believers from the unbelievers. In fact, the parables Allah strikes out provide a means whereby He leads astray many and guides many. But He leads astray only those who disobey His commands, namely the unbelievers and the hypocrites who violate the covenant they have made with Allah after having pledged to keep it, cut asunder whatever Allah has commanded to be joined, such as kinship bonds, among other commandments, and spread corruption in the land through unbelief, acts of disobedience and sins. It is these who have assuredly deprived themselves of the ultimate success, namely winning Allah’s mercy and attaining eternal bliss.
Allah then reproves those who disbelieve in Him for their unbelief, for how could they possibly deny Him despite the clear signs pointing to His existence and immense power, seeing that they were non-existent, then He brought them into existence by breathing spirit into them, then He will cause them to die, and will again restore them to life on the Day of Resurrection and they will be returned to Him for the final judgement?!
It is this Lord, Exalted and Sublime be He, who has created everything on the earth for you, all by His favour and grace, then He rose over towards the heavens and fashioned them into seven heavens to perfection, and He has full knowledge of everything.