“These will be granted their reward twice because they remained steadfast, they repel evil with good, and spend [in alms] out of the sustenance We provided them.”
(Al Qur’ān – 28:54)
This ayah presents some of the characteristics of the delegation of 20 Christians, who had come to Makkah and having got answers to their questions by the Prophet ﷺ, reverted to Islam.
They would receive double reward: one for their believing in Jesus and the other for believing in Muhammad (peace be to them both). The same was stated in a hadīth reported in Bukhārī and Muslim on the authority of Abū Mūsā al-Ash‘arī, whereby the Prophet ﷺ said: “Three persons will receive double reward: one of them is he who is from among the People of the Book and who believed in his own Prophet and then believed in Muhammad.”
These people will receive double reward because they followed the True Religion and kept themselves above national, racial and tribal prejudices. Later when the Prophet ﷺ came onto the scene they faced a serious test regarding their fidelity to God. They proved themselves to be truly worshippers of God, rather than worshippers of Jesus Christ, a servant and Prophet of God. Hence when a new Prophet came after Jesus with the same Islam which had earlier been expounded by Jesus, they followed the Guidance of the new Prophet. They did not hesitate to accept it and chose to abandon the path of those who clung to Christianity.