The meaning of the quality of Islam is the submission and fulfillment of all the acts of obedience whose judgment is clear. If one declares the all acts of obedience publicly, even if he does not believe with the heart, he will deserve the name and meaning of Islam, warrant the public friend-ship, his testimony will be accepted, the rulings of inheritance will be valid for him, and he will enjoy the rights and obligations of the Muslims. This is the quality of Islam.
The difference between the believer and the Muslim is that the latter will be believer when he is obedient intentionally along with his public declaration. If he obeys publicly only, he will be Muslim. If he obeys publicly and intentionally, he will be believer provided that submission and seeking favors through knowledge will be present. It happens that a servant is Muslim but not believer. No one can be believer unless he is Muslim.