If you’re absolutely sure you want to become a Muslim, all you need to do is recite the Shahada, a short oral declaration of faith. The words of the Shahada are “La ilaha illallah, Muhammadur rasulullah ” This translates to “I testify that there is no other god but Allah, and Muhammad is God’s messenger (prophet).” By saying the Shahada, you become a Muslim.
The first part of the Shahada (“La ilaha illallah”) refers not only to deities from other religions, but also to earthly things which can take the place of Allah in your heart – wealth and power, for example.
The second part of the Shahada (“Muhammadur rasulullah”) is a recognition that the word of Muhammad is the word of God. Muslims are required to live by the principles of Muhammad revealed in the Quran – the Shahada is a pledge to follow these principles.
The Shahada must be said with sincerity and understanding to be binding. You can’t become a Muslim just by pronouncing the words – the oral recitation is a reflection of belief that’s held in the heart.
To become a legal member of the Muslim community, have witnesses present at your recitation. Witnesses are not strictly required to become a Muslim – God knows all things, so a Shahada said alone, with conviction, will make you a Muslim in God’s eyes. However, to become legally recognized by the Muslim mosque, you generally must make your Shahada in front of witnesses – two Muslims or an Imam (Islamic religious leader) who is authorized to certify your new faith.
Wash yourself. Immediately upon becoming a Muslim, you should take a shower or bath as a form of purification. This is a symbolic act that signifies the washing away of the past and of emerging from darkness to light.
No one’s sins are too grave to prohibit newfound purity. Upon making your Shahada, your past sins are forgiven. You symbolically begin a new life centered around striving to improve your spiritual state through good deeds