Belief in One God
The most fundamental teaching of Islam is to believe in the Oneness of God, in the sense of His being the only Creator, Preserver, Nourisher, etc. But this belief is not enough. Many of the idolaters knew and believed that only the Supreme God could do all this and yet they associated other gods with Him. Therefore, one must acknowledge the fact that it is God alone who deserves to be worshipped, and thus abstain from worshipping any other thing or being. Likewise, Muslims believe that God has no father or mother, no son or daughter. None is equal to Him. He is God of all humankind, not of a special tribe or race.
Worship of God alone and no one else
The Qur’an, the divine Book of Islam, reminds us of the falsity of all alleged gods. To the worshippers of manmade objects, it asks,
“How can you worship things you carve with your own hands, when it is God who has created you and all your handiwork?” (Al-Saffat 37: 95-96)
At another point, God says,
“Say, ‘Why do you take protectors other than Him, who can neither benefit nor harm even themselves?’ Say, ‘Are the blind equal to those who can see? And are the depths of darkness equal to the light?’ Have the partners they assign to God created anything like His creation so that their creation is indistinguishable from His? Say, ‘God is the Creator of all things: He is the One, the All Compelling.’” (Al-Ra`d 13: 16)
To the worshippers of heavenly bodies the Qur’an cites the story of Abraham:
“When the night grew dark over him he saw a star and said, ‘This is my Lord,’ but when it set, he said, ‘I do not like things that set.’ And when he saw the moon rising he said, ‘This is my Lord,’ but when it too set, he said, ‘If my Lord does not guide me, I shall be one of those who go astray.’ Then he saw the sun rising and cried, ‘This is my Lord! This is greater.’ But when the sun set, he said, ‘My people, I disown all that you worship beside God. I have turned my face as a true believer towards Him who created the heavens and the earth. I am not one of the polytheists.’” (Al-An`am 6: 76-79)
Importance of Faith: Belief in God Unseen
Having achieved this knowledge of the One True God, one should constantly have faith in Him, and should allow nothing to induce them to deny the truth. When true faith enters a person’s heart, it impacts the person’s outlook and behavior. Prophet Muhammad, the final messenger of Islam, said, “Faith is that which resides firmly in the heart and which is proved by deeds.”
One of the striking results of faith is the feeling of gratitude towards God, which could be said to be the essence of worship.
Believers love, and are grateful to, God for the bounties He bestowed upon them. They are aware of the fact that their good deeds can never be equivalent to Divine favors, and therefore they are always anxious to please God. They remembers God often. The Qur’an promotes this feeling of gratitude by repeating the attributes of God very frequently.
“He is God: there is no god other than Him. It is He who knows what is hidden as well as what is in the open, He is the Lord of Mercy, the Giver of Mercy. He is God: there is no god other than Him, the Controller, the Holy One, Source of Peace, Granter of Security, Guardian over all, the Almighty, the Compeller, the Truly Great; God is far above anything they consider to be His partner. He is God: the Creator, the Originator, the Shaper. The best names belong to Him. Everything in the heavens and earth glorifies Him: He is the Almighty, the Wise.” (Al-Hashr 59: 22-24)
Taken with slight editorial modifications from www.whyislam.org.Soucre Link