Answered by Shaykh Shuaib Ally
Question: Assalam alaykum,
Through the years I heard believers take the shahada by saying: “Ashhadu an la ilaha il Allah wa ashhadu Ana Isa rasul Allah wa ashhadu Ana Mohamadan rasul Allah”. (I testify that there is no god but God and that Jesus is His messenger and that Muhammad is His messenger” Especially when the imam was convinced that the convert was Christian before. Is this correct?
Answer: Wa alaikum assalam wa rahmatullah,
The two primary components of the shahada are (1) the declaration of the oneness of God, and (2) the declaration that Muhammad (peace be upon him) is His messenger. This declaration, as it stands, is valid and complete.
As long as these two components are in place, there is no harm in adding to it if there is compelling reason to do so. Some have encouraged additions to allow for the person embracing Islam to renounce the belief system they had previously held. This is a position attributed to Abu Yusuf with respect to those embracing Islam from different religions [Kuwait Encyclopedia of Islamic Law].
It is possible that such additions find basis in the Prophet’s saying (peace be upon him), “Whoever says ‘I testify that there is no god but God; He is one, and has no partners; and that Muhammad is His servant and messenger; and that Jesus is a servant of God and a son of His female servant; and His word delivered to Mary; and spirit from Him; and that Paradise is true, and that the Fire is true,’ shall enter Paradise from any of its eight gates he so pleases” [Muslim].
God knows best.