(778 A.D., Author unknown)
The earliest written Christian apologetic, which was in Arabic and addressed to Muslims, was produced by an unknown Christian author in 788 A.D. The author of this short text was well aware of Muslim arguments against the Trinity, as well as the Qur'an's vocabulary, which he used to make his points.
This, then, is our faith and our testimony in God and His Word and His Spirit: He is the Father and the Son and the Holy Spirit, one God and one Lord. As for Christ, in him He saved and delivered mankind, and we shall expound that, God willing, how God sent His Word and His Light as a mercy and guidance to men, and favoured them by Him.
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