Do you bear witness that there's no god but Allah, or do you just say it? There's a strength or... 

Do you bear witness that there is no god but Allah, or do you just say it? There's a strength or a weakness. There's disbelief in the Taghut along with the Iman in Allah, both of which are a must.
{So whoever disbelieves in the Taghut and believes in Allah has grasped the most trustworthy handhold, which cannot be broken. And Allah is the All-Hearing, All-Knowing (256)
Allah is the ally of those who believe. He brings them out of darkness into light. And those who disbelieve, their allies are the Taghut. They bring them out the light into the darkness. Those are the companions of the Fire. They will abide therein forever (257)}
[Surat Al-Baqarah: 256-257]