La Ilaha Illa-Allah Its meaning, conditions, nullifiers, virtues, and syntactic analysis

Verily, the foremost matter individuals should put to effect is: To learn the purpose for which Allah created them, took the covenant upon them, sent His Messengers to them, sent down His divine scriptures. For this purpose, the worldly life, the Hereafter, the paradise and the hell-fire were created. Additionally, owing to this purpose, the Day of Judgement will be established, the scales of deeds will be set, the sheets of deeds will be scattered, and sorrow and happiness will be on that Day and on which light will be distributed.
Allah says,

"And he for whom Allah has not appointed light, for him there is no light."
Allah instructs us that we are created to worship Him. The backbone and foundation of worship is Tawheed; with which all the Messengers had been missioned to proclaim, The simple profession that comprises Tawheed in its entirety is very short, copious of implications, and critically significant; it is:

"La ilaha ill Allah"