The Path Of Truth
Know may God grant you success that a man came to the messenger peace be upon him and said to him which of the deeds is best? So the messenger peace be upon him said to him To believe in Allāh and His messenger. Hence, it is understood from that that there is no better deed than to have the correct belief because the one who has a sound belief, no matter how many sins he commits, as long as he dies as a muslim then he will be saved from dwelling forever in hellfire.
The basis of the correct belief is to know Allāh and the basis of knowing Allāh is clearing Allāh, The Exalted, from resembling the creation in any way whatsoever just as been revealed in the chapter of Ash-shura nothing resembles him in any way whatsoever and He is attributed with hearing and sight.