Explain the notion of Shahadah (the declaration of faith) in Islam

The oneness of Allah is the one most important theological principal in Islam. The first of the five pillars, the declaration of faith, which is the first act that one does to embark on Islam, reiterates the necessity of the belief in the oneness of Allah. It begins with the negation of any god other than Allah:"I bear witness that there is no god but Allah and that Muhammad is His messenger."Beginning with negation rather than affirmation, in this case, serves to emphasise strongly the importance of the oneness of Allah.