Then comes illa llah: ‘except Allah, the source of all creation. The second part of shahadah is Muhammadun rasulu’ lalah; ‘ Muhammad is the messenger of guidance has come through a man like ourselves.
Therefore, Iman is something which cannot and should not taken for granted, unfortunately, many of us take it for granted. If Iman is so important that it is the gist of life here and a savior in the hereafter, then it becomes necessary for each of us to find out what Iman really is. It is not right to say that I am Muslim and therefore I have Iman because I was born in a Muslim family.
According to the Quran, Iman is conviction which is based upon reason and knowledge ; a conviction that results from full mental acceptance and intellectual satisfaction; the kind of conviction that gives one a feeling of inner contentment and peace. And a Mumin is one who accepts truth in such a way that it ensures his own peace and helps him to safeguard the peace and the security of the rest of mankind. In fact, Al-Mumin is one of the attributes of god himself
هُوَ اللَّهُ الَّذِي لَا إِلَهَ إِلَّا هُوَ الْمَلِكُ الْقُدُّوسُ السَّلَامُ الْمُؤْمِنُ الْمُهَيْمِنُ الْعَزِيزُ الْجَبَّارُ الْمُتَكَبِّرُ سُبْحَانَ اللَّهِ عَمَّا يُشْرِكُونَ ﴿23﴾ he is allah, besides whom there is no god; the king, the holy, the giver of peace, the granter of security, guardian over all, the mighty, the supreme, the possessor of every greatness glory be to allah from what they set up (with him) (23)
It is better to see something once for yourself than to hear about it a hundred times.