Tertullian on the Divinity of the Holy Spirit in 210CE

Now, what the Holy Spirit is, we are taught in many passages of Scripture, as by David in the fifty-first Psalm when he says, “And do not take Your Holy Spirit from me;” and by Daniel, where it is said, “The Holy Spirit which is in you.” And in the New Testament we have abundant testimonies, as when the Holy Spirit is described as having descended upon Christ, and when the Lord breathed upon His apostles after His resurrection, saying, “Receive the Holy Spirit;” and the saying of the angel to Mary, “The Holy Spirit will come upon you;” the declaration by Paul, that no one can call Jesus Lord, except by the Holy Spirit. In the Acts of the Apostles, the Holy Spirit was given by the imposition of the apostles’ hands in baptism.

From all which we learn that the person of the Holy Spirit was of such authority and dignity, that saving baptism was not complete except by the authority of the most excellent Trinity of them all, i.e., by the naming of Father, Son, and Holy Spirit, and by joining to the unbegotten God the Father, and to His only-begotten Son, the name also of the Holy Spirit. Who, then, is not amazed at the exceeding majesty of the Holy Spirit, when he hears that he who speaks a word against the Son of man may hope for forgiveness; but that he who is guilty of blasphemy against the Holy Spirit has not forgiveness, either in the present world or in that which is to come! …

This is most clearly pointed out by the Apostle Paul, when demonstrating that the power of the Trinity is one and the same, in the words, “There are diversities of gifts, but the same Spirit; there are diversities of administrations, but the same Lord; and there are diversities of operations, but it is the same God who works all in all. But the manifestation of the Spirit is given to every man to profit withal.” From which it most clearly follows that there is no difference in the Trinity, but that which is called the gift of the Spirit is made known through the Son, and operated by God the Father. “But in all these works that one and the same Spirit, dividing to every one individually as He will.”