No. The foundation of the belief is that anyone believes in One God and his message ( as we all must); can not negotiate the faith or believing God and His true Message. Islam is the whole mean is derived from the Arabic root "Salema": peace, purity, submission and obedience. In the religious sense, Islam means submission to the will of God and obedience to His law.
Everything and every phenomenon in the world other than man is administered totally by God-made laws, ie. they are obedient to God and submissive to his laws, they are in the State of Islam. Man possesses the qualities of intelligence and choice, thus he is invited to submit to the good will of God and obey His law, ie, become a Muslim.
Submission to the good will of God, together with obedience to His beneficial Law, ie, becoming a Muslim, is the best safeguard for man's peace and harmony.
Islam dates back to the age of Adam and its message has been conveyed to man by God's prophets and messengers, including Abrahim, Moses, Jesus and Muhammad.
Islam's message has been restored and enforced in the last stage of the religious evolution by God's last prophet and messenger, Muhammad.
The word Allah in the Arabic language means God, or more accurately, The One and Only Eternal God, Creator of the Universe, Lord of all lords, King of all kings, Most Compassionate, Most Merciful. The word Allah to mean God is also used by Arabic speaking Jews and Christians.
Its batter to be a Muslim than Just believe in God and not believe in guidance or just blindly following a faith, as it has much influence of Human beings.