You should know that the reward for the one who acts upon Tawhid *which is to single out Allah alone with worship) is bliss, honour, happiness and eternal paradise.  This is what Allah has promised the one who worships Him alone and abandons polytheism (shirk).  And the recompense for the one who is heedless of Tawhid, does not worship Allah or worships others along with Him, is that Allah will make him lowly and punish him in the Hellfire and he will remain therein.