How to be a mu'min, how to be a believer ? One day... a man asked to Messenger of Allah. He Said :" O Muhammad, tell me about Iman ?" The Messenger of Allah Said is to believe in Allah " What does it mean to believe in Allah ? Believe (Iman) in Allah. Believe in the existence of Allah, believe that Allah Alone is The Lord without any partners. He is Allah the One; The Self-Sufficient Master whom all creatures need. He is neither eats nor drink. He begets not, nor was begotten. And there is no one equal or comparable unto him.
The Second Pillar, to become a believer. To believe in His angels. Angels of Allah. The third Pillar, to believe in His Book, like The Quran, the Gospel and the Taura. The Fourth Pillar, to believe in His messengers. Like prophet Moses, Jesus and Muhammad (may the blessings and peace of Allah upon him). The Fifth Pillar, to be a believer, to be a mu'min, to believe the Last Day, the Day of Judgement. After the life of this world there is an afterlife. The Sixth, the last Pillar, to become a believer. To believe in divine destiny , both the good and the evil thereof. I do hope you become a believer, to be a mu'min.
If Someone : To believe in Allah,; To believe in His angels (angels of Allah); To believe in His messengers (Muhammad SAW etc.); To believe in His Books ( like The Quran, the Gospel etc.); To believe in the Last Day (The Day of Judgement); and To believe in divine destiny both the good and the evil thereof. He has become a believer, he has become a mu'min. Wallahu 'alam bish-shawab.