What are the best simple ways to demonstrate the greatness of Allah Almighty in contemporary reality, and what are the reasons for strengthening one's certainty in Him?

Among the most beneficial ways to instill faith in Allah and demonstrate His greatness is to recount Allah's cosmic signs, substantiated by Quranic verses, prophetic traditions (Hadith), and scientific discoveries, and to ponder over everything our senses encompass. Contemplation of the harmonious and perfect universe leads a person to conclude that it must have a magnificent Creator, who is Allah, the Most High. Quranic verses abound in encouraging reflection and contemplation of Allah's creations, because the process of creation is one of the greatest proofs of Allah's greatness. Certainty in Allah also increases through a heartfelt turning to His remembrance and worship, and an increase in proximity to Him. Therefore, contemplation of Allah's creation combined with His remembrance and worship are indispensable. Allah the Almighty said: "Indeed, in the creation of the heavens and the earth and the alternation of the night and the day are signs for those of understanding. Those who remember Allah while standing or sitting or [lying] on their sides and give thought to the creation of the heavens and the earth, [saying], 'Our Lord, You did not create this in vain; exalted are You [above such a thing]; then protect us from the punishment of the Fire.'"