Clement: "we understand, then, the Unknown, by divine grace, and by the word alone"

“It remains that we understand, then, the Unknown, by divine grace, and by the word alone that proceeds from Him; as Luke in the Acts of the Apostles relates that Paul said, "Men of Athens, I perceive that in all things ye are too superstitious. For in walking about, and beholding the objects of your worship, I found an altar on which was inscribed, To the Unknown God. Whom therefore ye ignorantly worship, Him declare I unto you.””

(λείπεται δὴ θείᾳ χάριτι καὶ μόνῳ τῷ παρ' αὐτοῦ λόγῳ τὸ ἄγνωστον νοεῖν, καθὸ καὶ ὁ Λουκᾶς ἐν ταῖς Πράξεσι τῶν ἀποστόλων ἀπομνημονεύει τὸν Παῦλον λέγοντα· ἄνδρες Ἀθηναῖοι, κατὰ πάντα ὡς δεισιδαιμονεστέρους ὑμᾶς θεωρῶ. περιερχόμενος γὰρ καὶ ἀναθεωρῶν τὰ σεβάσματα ὑμῶν εὗρον καὶ βωμὸν ἐν ᾧ ἐπεγέγραπτο· "7ἀγνώστῳ θεῷ."7 ὃν οὖν ἀγνοοῦντες εὐσεβεῖτε, τοῦτον ἐγὼ καταγγέλλω ὑμῖν.) (Str. 5.12.82.4)

"God always remains a mystery"

“This is because in Himself, according to His essence, God always remains a mystery. He expresses His natural hiddenness to the same degree that He makes it the more hidden through the revelation” (Maximus, Cap. 1.9) (PG 90:1181C)

"everything would be shattered if God revealed Godself in power and glory"

God reveals Godself by the fleeting method of the word, and in an appearance of weakness, because everything would be shattered if God revealed Godself in power and glory and absoluteness, for nothing can contain God or tolerate God's presence. Jacques Ellul, Jacques Ellul: Essential Spiritual Writings

"It was not without the wood of the tree that He came to our knowledge."

Moses says, “Show Thyself to me,”—intimating most clearly that God is not capable of being taught by man, or expressed in speech, but to be known only by His own power. For inquiry was obscure and dim; but the grace of knowledge is from Him by the Son. Most clearly Solomon shall testify to us, speaking thus: “The prudence of man is not in me: but God giveth me wisdom, and I know holy things.” Now Moses, describing allegorically the divine prudence, called it the tree of life planted in Paradise; which Paradise may be the world in which all things proceeding from creation grow. In it also the Word blossomed and bore fruit, being “made flesh,” and gave life to those “who had tasted of His graciousness”; since it was not without the wood of the tree that He came to our knowledge. For our life was hung on it, in order that we might believe. (ἐκρεμάσθη γὰρ ἡ ζωὴ ἡμῶν εἰς πίστιν ἡμῶν.)” (Clement, Str. V 71,5-V 72,4)

Maximus on the Word being concealed while revealed

 For the Word, who created the universe and established the law, is concealed in His manifestation, being invisible according to nature; and He is manifested through concealment, assuring those who are wise that by nature He cannot be apprehended.
– Maximus, Amb. 10.18.1129C

Henry Suso: "How should man better know the hidden things of God than in His assumed Humanity?"

”The bottomless abyss of My hidden mysteries (in which I order everything according to My eternal providence), let no one explore, for no one can fathom it. And yet, in this abyss, what thou askest about and many things besides are possible, which yet never happen. However, know this much, that, in the order in which emanated beings now are, a more acceptable or more pleasing way could not be. The Lord of nature knows well what He can do in nature. He knows what is best suited to every creature, and He operates accordingly. How should man better know the hidden things of God than in His assumed Humanity? How might he, who has forfeited all joy through irregular lusts, be rendered susceptible of regular and eternal joy? How would it be possible to follow the unpracticed way of a hard and despised life, unless it had been followed by God Himself? If thou didst lie under sentence of death, how could He, who should suffer the fatal penalty in thy stead, better prove His fidelity and love towards thee, or better excite thee to love Him in return? Him, therefore, whom My unfathomable love, My unspeakable mercy, and My bright divinity, My most affable humanity, brotherly truth, espousing friendship, cannot move to ardent love, what else shall soften his stony heart? Ask the fair array of all created beings if ever I could have maintained My justice, evinced My fathomless mercy, ennobled human nature, poured out My goodness, reconciled heaven and earth, in a way more efficacious than by My bitter death?” (Suso, Little Book of Eternal Wisdom, Chap. 2)

Origen on the three ways of middle platonism being insufficient and the need for revelation

"Celsus thinks that God is known either by synthesis with other things, similar to the method called synthesis by geometricians, or by analytical distinction from other things, or also by analogy, like the method of analogy used by the same students, as if one were able to come in this way, if at all, 'to the threshold of the Good' (Pl. Phil. 64c, Clem. Strom. VII,45,3). But when the Logos of God says that 'No man has known the Father except the Son, and the man to whom the Son may reveal him', he indicates that God is known by a certain divine grace, which does not about in the soul without God's action, but with a sort of inspiration." (Con. Cel. VII,44)

Origen on the insufficiency of human nature and the need for revelation

"[...]human nature is not sufficient in any way to seek for God and to find Him in His pure nature, unless it is helped by the God who is object of the search. And He is found by those who, after doing what they can, admit that they need Him, and shows Himself to those to whom He judges it right to appear, so far is it is possible for God to be known to man and for the human soul which is still in the body to know God." (Con. Cel. VII,42)

Origen on Jesus as the divine moral teacher

"[...]because of his exceeding love towards man he was able to give the educated a conception of God which could raise their soul from earthly things, and nevertheless came down to the level even of the more defective capacities of ordinary men and simple women and slaves, and, in general, of people who have been helped by none but by Jesus alone to live a better life, so far as they can, and to accept doctrines about God such as they had the capacity to receive." (Con. Cel. VII,41)

Origen on the deficiency of the human will and the need for God's creative action

"[...]since our will is not sufficiently strong for us to be entirely pure in heart, and because we need God to create it entirely pure, the man who prays with understanding says 'Create in me a clean heart, O God.'" (Con. Cel. VII,33)

Origen on the knowledge of God and revelation by providence

"The knowledge of God is not derived from the eye of the body, but from the mind which sees that which is in the image of the Creator and by divine providence has received the power to know God." (Con. Cel. VII,33)

Origen on Christ being the power and wisdom of God

"[...]if by wisdom one understands Christ, since Christ is the power of God and the wisdom of God, we say not only that a man wise in this sense can come to the Father, but also that the man adorned with the spiritual gift called 'the word of wisdom', which is conferred by the Spirit, is far superior to people who are not so adorned." (Con. Cel. VII,23)

Origen on the origin of evil and the need of grace for understanding evil

"Each person's mind is responsible for the evil which exists in him, and this is what evil is. Evils are the actions which result from it. In our view nothing else is strictly speaking evil. However, I know that the problem requires an extended discussion and argument which, by the grace of God illuminating the mind, can be done by one who is judged by God to be worthy even of knowledge of this subject." (Con. Cel. IV,66)

Origen on hearing the voice of God

"[...] the divine voice is such that it is heard only by those whom the speaker wishes to hear it. [...] And since when God speaks He does not want His voice to be audible to all, a man who has superior hearing hears God, whereas a man who has become hard of hearing in his soul does not perceive that God is speaking." (Con. Cel. II,72)

Origen on revelation and scripture

"Jesus taught us who it was that sent him in the words 'No man has known that Father save the Son', and in this, 'No man has seen God at any time; the only begotten God who is in the bosom of the Father, he has declared him.' He revealed to his true disciples the nature of God and told them about His characteristics. We find traces of these in the scriptures and make them the starting-point of our theology." (Con. Cel. 2,72)