The Declaration of Faith is the phrase one utters to become a Muslim. It is the expression of one's firm belief in the oneness of Allah and willingness to totally submit to His Will.
When one pronounces the declaration of faith one says: "Ash -hadu an laa ilaha ilia Allah, wa ashadu anna Muhammadan Rasuulu Allah", which in English means, "I bear witness that there is no deity except Allah, and I bear witness that Muhammad is the last Messenger of Allah."
The impact of the declaration of faith on one's behavior is quite significant. A person who bears witness that all authority and power is with Allah, and that Muhammad is His Messenger will naturally desire to learn and obey all commandments of Allah's Holy Book, the Qur’an, and the teachings of Prophet Muhammad (peace be upon him).
Such belief leads to the development of a just and merciful society, as both ruler and ruled obey Allah. All are servants of Allah, and Allah is recognized as Master of all, regardless of race, wealth or lineage.