Unitaria.--The Fathers before the Council of Nice speak rather like Arians than orthodox. If any one desire to see undeniable proofs of it, I refer him to the Quaternio of Curciltaus, where he will be fully satisfied. There is scarcely one text alleged to the Trinitarians which is not otherwise expounded by their own writers: you may see a great number of these texts and expositions in a book entitled Scriptura S. Trin. Revelatrix, under the name of St Gallus. There be a multitude of texts that deny those things of Christ which cannot be denied of God, and that affirm such things of him that cannot agree to him if he were a person of God..If you go through his list for and against the Trinity, there's no debate anymore. He quotes the Father of Unitarianism John Biddle, and neglects most of the New Testament that mentions the Trinity. By this work--which was private, and thank God for his sake it was, Locke was actually an amateur theologian (citing uninspired men) if he can be called one. The last sentence of the first paragraph proves Locke denied Christ's Deity. He agrees that this "Curcillaeus has proved..special union of three persons in the Deity." Locke even mocks the Trinity "Concerning the original of the Trinitarian doctrines..or by whom they were invented." Locke was wrong about the Church Fathers and the Trinity, as well as Divinity of the Holy Spirit.
Trinity.—The Papists deny that the doctrine of the Trinity can be proved by the Scripture ; see this plainly taught and urged very earnestly by Card. Hosius de Auth. S. Script. 1. iii. p. 53; Gordonius Hunlaeius Contr. Tom. Cont. de Verbo Dei, c. 19; Gretserus and Tanerus in Colloquio Rattisbon. Vega. Possevin. Wiekus. These learned men, especially Bellarmin, and Wiekus after him, have urged all the Scriptures they could, with their utmost industry, find out in this cause, and yet, after all, they acknowledge their insufficiency and obscurity.
Curcillaeus has proved, as well as anything can be proved out of ancient writings, that the doctrine of the Trinity, about the time of the Council of Nice, was of a special union of three persons in the Deity, and not of a numerical, as it is now taught, and has been taught since the chimerical schoolmen were hearkened unto.Trinity.—The Divinity of the Holy Spirit was not believed, or, as I think, so much as mentioned, by any in the time of Lactantius, i. e. anno 300..
Yet the Church Fathers spoke of the numerical Trinity years before Nicea:
And at the same time the mystery of the oikonomia is safeguarded, for the unity is distributed in a Trinity. Placed in order, the three are the Father, Son, and Spirit. They are three, however, not in condition, but in degree; not in being, but in form; not in power, but in kind; of one being, however, and one condition and one power, because he is one God of whom degrees and forms and kinds are taken into account in the name of the Father, and of the Son, and of the Holy Spirit.--Tertullian, 216 A.D. Against Praxeas 2
The Father's Word, therefore, knowing the economy and the will of the Father, to wit, that the Father seeks to be worshipped in none other way than this, gave this charge to the disciples after he rose from the dead: "Go ye and teach all nations, baptizing them in the name of the Father, and of the Son, and of the Holy Ghost." (Matt 28:19) And by this he showed that whosoever omitted any one of these, failed in glorifying God perfectly. For it is through the Trinity that the Father is glorified. For the Father willed, the Son did and the Spirit manifested.--Hippolytus of Rome, 220 A.D. Against Noetus Ch. 14.
For this cause, yea and for all things, I praise Thee, I bless Thee, I glorify Thee, through the eternal and heavenly High-priest, Jesus Christ, Thy beloved Son, through whom with Him and the Holy Spirit be glory both now [and ever] and for the ages to come. Amen.--Polycarp of Smyrna, 155 A.D. To Autolycus 2:15