My brothers and sisters in Islam, As-salamu ‘alaikum!
To testify that there is One Creator who sustains, nourishes, and controls is not enough for the Muslim. The Muslim is one who believes and testifies that indeed Allah is the Creator, the Nourisher, the Sustainer, and also affirms that ONLY He is worthy of worship.
Our testimony of faith is not, ‘La Rabba ill Allah’ (There is no Lord except Allah), because if this was the case then even the mushrikeen of the time of our beloved Prophet (صلي الله عليه وسلم) believed and testified that Allah was the sole Creator.