Islam is the Religion of all the Prophets of Allah starting with Adam and ending with Muhammad. In Arabic Islam means submission. To believe in the heart and declare with the tongue: “No one is God except Allah and Muhammad is the Messenger of Allah” is how one becomes Muslim. Utterance with the Two Professions (ashShahadatan) is required of the person who is not already a Muslim. A Muslim is a believer and a follower of Islam.
The First Profession (ash-Shahadah), i.e., “No one is God except Allah” means nothing deserves to be worshipped except Allah. “Allah” is the name of the Creator in Arabic which means “The One Who has the Godhood which is the power to create the entities.”
The second Profession, i.e., “Muhammad is the Messenger of Allah” includes believing Muhammad was the last of the prophets, he was truthful in all he told about and conveyed from Allah (as were all the prophets before him), and the Creator gave us prophets and messengers (A ‘prophet’ is a man who receives the Revelation from Allah and conveys it to the people. A ‘messenger’ is a prophet who comes with some new laws. The prophet who is not a messenger follows the laws of the messenger who came before him. Every messenger is a prophet, but not every prophet is a messenger.) to guide us to worship Him correctly. A Muslim must believe in all the prophets and messengers.
The Two Professions are the essentials of belief in Islam; they are the foundation of the faith. The analogy of constructing a building is useful in explaining the importance of this basic belief. There will be no building without a concrete foundation. Likewise, there will be no benefit and fruitful results in the Hereafter without having the correct belief first.