weakness

Respected scholars, as-salamu `alaykum.the Islamic world today is clearly disunited, and it is this disunity that has been one of the core reasons I think for the weaknesses of Muslims as a nation. What would it take in your view for Muslims the world over to be united in voice and action?and how is it that each group seems to be convinced that it is on the "right" path as much as it condemns the other Muslim groups for not being so?thank you.