The concept and reality of Iman in Allah True Iman is life to the soul and a source of happiness
The soul's contentment is attained only through belief in Allah(mighty and majestic is He). An unbelieving soul remains insecure, scared, lost and weak, with no stability. The only belief that leads to deliverance is the belief in Allah. It means the firm ratification that Allah is the Lord of everything, the King and Creator of everything, and He alone is worthy to be singled out for worship in Salah (prayers), Sawm (fasting), Du'aa (supplication), when having hope and fear, and being humble and submissive. He (mighty and majestic is He) alone has all the perfect attributes, being exalted from any deficiency or defect. Iman in Allah is the light that guides to justice, freedom and knowledge. It is the light that guides to the straight path; the light that leads us to spiritual tranquility and security.
Belief in Allah includes belief in His angels, scriptures, messengers, the Last Day and fate, whether good or evil. This belief is the origin of human happiness. It is the Jannah of the believer in this world and leads him, Allah Willing, to the Jannah of the Hereafter.
Faith in Islamic Shari'a is: Belief with the heart, utterance with the tongue, actions with the body parts, increases with the obedience of god and decreases with disobedience of god (decreases with the obedience of Satan).
If this is realized, then it should be known that the bases upon which Allah accepts our deeds is Iman. Allah (mighty and majestic is He) says: "So whoever does righteous deeds while he is a believer" (Al-Anbiyâ': 94).