Why is it necessary to follow a Mujtahid?

Answer

It is necessary for a Muslim to believe in the fundamentals of faith with his own insight and understanding, and he cannot follow anyone in this respect i.e. he cannot accept the word of another who knows, simply because he has said it. However, one who has faith in the true tenets of Islam, and manifests it by his deeds, is a Muslim and Mo'min, even if he is not very profound, and the laws related to a Muslim will hold good for him. In matters of religious laws, apart from the ones clearly defined, or ones which are indisputable, a person must act according to the verdicts (Fatwa) of the most learned Mujtahid.