It is very important to note that the Shiites are generally considered Muslims. This is how Islam views them. As for the issue of how they differ from Sunnis, it is necessary to keep in mind that Islam calls for unity and solidarity. Both Sunnis and Shiites are required to work together and try to overcome their points of difference or forget about them, simply because the Ummah is facing a plight.
Elaborating on this, the eminent Muslim scholar Sheikh Muhammad `Ali Al-Hanooti, member of the North American Fiqh Council, states: Now for the time being, I do not like to go into details of differences, but I want to bring every Muslim’s attention to certain basic beliefs.
First, we do believe in the Qur’an as it is available and accessible to every Muslim. And anyone who believes there is any other Qur’an is not a Muslim.
Second, we don’t believe in infallibility of any human being other than prophets. And the belief that any other than Prophet Muhammad (peace and blessing be upon him) could be infallible is alien to the beliefs of a Muslim.
Third, we believe that the Companions of the Prophet (peace and blessings be upon him) are our best examples after the Prophet (peace and blessings be upon him) himself, as the verse of surat at-Tawbah calls them the early forerunners of immigrants and supporters, etc. Allah is pleased with them, so there is no way for us to be displeased with them.
Anyone who agrees with those principles reminds me of the Prophet’s saying, “The one who makes our Prayer, directs his face towards our Qibla, and eats our slaughtered animals is a Muslim.” This means that he or she is our brother or sister in Islam.