The question was posed that even certain opponents claim to receive revelations, so how can one identify a truthful person and one who is a liar?
The Promised Messiahas said:
This is very straightforward. Any such claimant should come before us and publish the claim that if they are truthful, then the one who opposes them should die in their lifetime. I have been granted unwavering certainty from God Almighty that even if a ten-year-old child, who possesses all the provisions of this world and has their entire life ahead of them, were to make such a claim and stand in opposition to me, Allah the Almighty would cause them to die before me. (15 January 1898)
Doctrines of the Shia faith
The Shia doctrine is diametrically opposed to Islam. Firstly, it is a Shia doctrine that Gabriel erred in bringing down revelation. Secondly, they believe that the companions who were gained as a result of the prayers of the Messenger of Allah, peace and blessings of Allah be upon him, were, God forbid, not Muslim. Thirdly, the Noble Quran, is the Holy Book of Allah the Almighty and God himself promised to safeguard it, yet the Shias believe that the Holy Quran is no longer present in its original form. They believe that the original Quran has been taken into hiding by the Imam Mahdi. Fourthly, they believe that sainthood is limited to the twelve Imams and until the Day of Resurrection, all the rest of mankind are as savages and that God Almighty has no love for them. Fifthly, they hold that cursing the companions of the Holy Prophet, peace and blessings of Allah be upon him, who was the beloved of God, is more worthy of spiritual reward than invoking blessings upon the Holy Prophetsa. Sixthly, they do not consider any of the saints or pious people to be righteous. I have heard from one of my teachers say that Hazrat Syed Abdul Qadir Jilanirh would use foul language. The fact of the matter is that Yazid is most disgraced. As far as his involvement in the martyrdom of Imam Husainra is concerned, he is responsible for this evil, but the Shias of today, even collectively, could not offer the religious services that he rendered.
(Hazrat Mirza Ghulam Ahmadas, Malfuzat, Vol. 1, pp. 150-151)