Sermon 5 is the longest sermon in the series of 12 sermons On the Incomprehensible Nature of God, but like the previous two sermons Chrysostom has lengthy conclusion that has little to do with the stated thesis of the series as the final third of the sermon deals with the subject of prayer (43-62). 
Chrysostom deals intricately with the texts of John 1:18 and 6:46, “No one has ever seen God. The only begotten Son, who is in the bosom of the Father, himself declared him. Not that anyone has seen the Father except him who is from God, he has seen the Father.” The fact that “no one” has seen the Father except the Son is not meant to exclude the Holy Spirit, but all created beings (5-6). For support, Chrysostom turns to Paul’s words in 1 Cor. 2:11, “For who knows a person’s thoughts except the spirit of that person, which is in him? So also no one comprehends the thoughts of God except the Spirit of God” (7). This is certainly delicate reasoning, but it is sound. “No one” cannot exclude the Spirit in John or the Son in 1 Corinthians. Because we know God’s word is true and his testimony concerning himself is trustworthy, John 1:18; 6:46; and 1 Cor. 2:11 must all be true. So “no one” must indeed refer to all creatures outside of the Trinitarian communion.
Chrysostom then enters into a discussion that is, frankly, an amazing display of exegesis. The preacher turns his attention to 1 Corinthians 8:6, “yet for us there is one God, the Father, from whom are all things and for whom we exist, and one Lord, Jesus Christ, through whom are all things and through whom we exist.” As “no one” separates the Trinity from all creation, so “one” separates the Trinity to itself. To prove the equality of the Son and Father Chrysostom demonstrates that “God” and “Lord” are used interchangeably of the Father and Son. Paragraph 12 offers a concise summary,
Some names are common to several; others are proper to one. There are common names to show that the essence is exactly the same; there are proper names to characterize what is proper to the personal realities. The names “Father” and “Son” characterize what is proper to the personal realities; the names “God” and “Lord” show what is common. Therefore, after Paul set down the common name of “one God,” he had to use the proper name so that you might know of whom he was speaking. He did this to prevent us from falling into the madness of Sabellius.
The preacher then goes through Old and New Testament Scriptures demonstrating that the Father and Son are each called Lord and God (13-24). Returning to his main text, Chrysostom again asserts that knowledge necessitates identity. As men do not know the essence of angels, so neither angels nor men know the essence of God. The preacher goes even further in an amusing fashion. Not only are men incapable of knowing the essence of angels or God, they are incapable of knowing their own essence:
And why should I speak of what kind of essence the soul has? It is not even possible to say how it exists in the body. What answer could anyone give to this question? That it is extended throughout the bulk of the body? But that is absurd. To exist that way is proper only to bodies. That this is not the way that the soul exists in the body is clear from this example. If a man’s hands and feet are amputated, the soul remains whole and entire and is in no way mutilated by the maiming of the body.
Then it does not exist in the whole body but has it been gathered together in some part of the body? If that is true, the rest of the parts must be dead, because whatever lacks a soul is altogether dead. But we cannot say that. What we must say is that we know not that the soul is in our bodies but that we do not know how it is there. God has shut us off from this knowledge of the soul for a reason. So that, out of his great superiority, he might curb our tongues, hold us in check, and persuade us to remain on earth and not to meddle out of curiosity with matters which are beyond us. (28-29)
This also points to an important conclusion to be made plain before Chrysostom turns his attention to prayer. There is something inherently off-putting to the statement that a person cannot comprehend God. Even when time is taken to explain weight of “comprehend”; even when it is acknowledged that things can be truly known of God; for some it is hard to hear that God cannot be known in his essence. Chrysostom has a helpful analogy:
Tell me this. Suppose that two men are obstinately arguing with each other about whether they can know how large the sky is. Suppose that one of them says that it is impossible for the human eye to encompass it, and the other would contend that it was possible for a man to measure the entire sky by using the span of his hand. Which of these two would we say would know the size of the sky? Would it be the one who argues how many spans wide the sky is? Or would it be the one who admits that he does not know? Surely the man who admits he does not know the size of the sky when he sees its magnitude will have a better understanding of how large the sky is. When it is a question of God, will we not use the same discretion? Would it not be the ultimate madness if we failed to do so? (39)
Underlying the sermons of Chrysostom is a trust in the word of Scripture. This trust underlies his philosophy and epistemology too. It is not adventurous, brave, or noble, to go beyond the bounds of Scripture. It is folly and madness. Neither is it weak or ignoble to rest content in the knowledge that Scripture does provide. To stay within the bounds of Scripture is true security, it is full sanity.
 All paragraph references refer to those in Paul W. Harkins, St John Chrysostom On the Incomprehensible Nature of God (Washington, D.C.: The Catholic University of America Press, 1984).