In the first place, we would like to anchor the basic concept that Shiites are generally considered to be Muslims. All Muslims should be alert against the schemes and plots planned by the enemies of Islam. They are the ones that want us to disagree and fight each other. We should not give them this chance.
In this regard, we would like to cite for you the following by Dr. Muhammad Ahmad Siraj, a professor of Islamic Studies at the American University: “Sunnis and Shiites are Muslims who pray to the same God. Both believe in the same Qur’an, have faith in the same message of the Prophet (peace and blessings be upon him).
It is high time for the Muslim Ummah to appreciate all the segments of this Ummah and to have common understanding and appreciation of the Islamic faith.
The Qur’an calls us to unite and cooperate and avoid causes of dissent. Allah Almighty says: “And hold fast, all of you together, to the cable of Allah, and do not separate. And remember Allah’s favor unto you: how ye were enemies and He made friendship between your hearts so that ye became as brothers by His grace; and (how) ye were upon the brink of an abyss of fire, and He did save you from it. Thus Allah maketh clear His revelations unto you, that haply ye may be guided.” (Al `Imran 3: 103)
This does not mean that one is required to relax one’s understanding of the principles of Islam for the sake of unity with others but to live with them and appreciate what they have. Let’s try to cooperate on our common interpretations and excuse each other in case of difference.”
In light of what is mentioned above, we can conclude that a Shiite Muslim can pray behind a Shiite, and the opinion of the local scholar is quite right as Shiites are considered Muslims. With this in mind, we do admit that dubbing people with disbelief is one of the worst things a Muslim can do. It is actually a very serious sin to do as the only One who knows it is Almighty Allah. Of course, there are signs but still our role is clarify the truth and we are not judges. Finally, we advise you not to reject anyone wishing to pray behind you as it maybe through his prayer behind you that Allah grants him hidayah.
May Allah grant us all insight to understand the teachings of Islam.