Tawheed is the key

The Prophet Said:

There is no one amongst you that makes Wudoo’, and does so perfectly, and then says, ‘I Testify that there is no deity worthy of worship except Allaah. He is alone, having no partners. And I bear witness and testify that Muhammad is His slave and Messenger’, except that all eight doors of Paradise are opened for him, and he can enter into it through whichever one he pleases.

Reported by Muslim (#234) and others.