THE QUR'ANIC TESTIMONY OF THE HOLY SPIRIT:
To our Muslim Brothers:
You must believe in God the Father. You name Him Allah, that is another topic. God has a Spirit, The Holy Spirit. You must believe in the Holy Spirit. The Quran speaks of the Holy Spirit. So you already believe in Two Hypostasis of The Trinity.
Many verses of the Qur'an mention that the Holy Spirit is the Spirit of God and that He supported the Lord Jesus with it. This becomes clear from the following:
Sura 2: 253
These messengers; we blessed some of them more than others. For example, GOD spoke to one, and we raised some of them to higher ranks. And we gave Jesus, son of Mary, profound miracles and supported him with the Holy Spirit.
Sura al-Ma'ida 5:110, "Allah said to Jesus, 'Jesus, son of Mary, remember the favour I had bestowed on you and your mother, how I strengthened you with the Holy Spirit, so that you preached to men in your cradle and in the prime of manhood."
The theological scholar Al-Shaikh Muhammad al- Hariri al-Bayyumi says, "The Holy Spirit is the spirit of Allah (Kitab al-Ruh wa Maiyyyatuha, p.53)
From all that preceded, my friend, the testimony of the Qur'an and the theologians of Islam for the creed of the Trinity in whom we Christians believe becomes clear."
Sura 16: 102: Say, "The Holy Spirit has brought it down from your Lord, truthfully, to assure those who believe, and to provide a beacon and good news for the submitters."