I would like what are the commonalities between Shiaism and sunnism. The best it can be said is Shias are 'Muhids" but not Muslims. If we wish to increase the number of Muslims the it is a political issue and not religious one?
We may of course make up our own criteria for who is and who is not Muslim. Most of the times, this practically ends with considering all who agree with us Muslims and all who disagree with us non-Muslims.
However if we decide to go with the criteria that God has mentioned in verse 9:11, then the criteria will be as follows:
- Not to be Mushrik and repenting from it
- Establishing daily prayers in the life
- Paying Zakah
As far as I know, Shia Muslims are not Mushrik, they pray and they pay Zakah. If I consider them as non-Muslim then I am disregarding the above mentioned verse.
Besides, please bear in mind that no individual has the authority to announce someone as Non-Muslim. It is only the state of Muslims that has that authority.