Say No To False Deities.

As-Salaam alaikum, 
   For every Muslim, by saying 'LA ILAHA (there is no deity) he or she says no to every sort of pseudo-deity, and by saying ILLAL ALLAH (but Allah), one says' Yes' to God alone.

 The negation of other-than-Allah is seen as the precondition of the affirmation of Allah Ta'ala, just as ritual purity precedes prayer, or cleaning a house of dirt precedes the arrival of a King therein... thus, for this reason it is necessary that 'La ilaha illallah.. this is the simplest expression of the affirmation of the Oneness of Allahu, Tabaraka Wa Ta'ala.