The answer to the grammar came through Susan.
This is the answer to "Who is the son of man in Matthew 16:13?"
The short answer: He is the words that come out of your mouth.
The Long Answer
To show the Hebrew classification of the metaphor.
“God is not a man, that He should lie, Nor a son of man, that He should repent; Has He said, and will He not do it? Or has He spoken, and will He not make it good? (Numbers 23:19 NASB)
This verse shows that there's a division between the classification of God and the metaphor "Son of Man".
This metaphor was used much in both the book of Ezekiel and that of the Book of Enoch. Now regardless if one wants to discount the Book of Enoch, its been described that the Book of Enoch was popular during the time of Jesus. And even if that's disagreed with, it still was used in that writing holding to the concept of the metaphor.
God is the Word
In the beginning was the Word, and the Word was with God, and the Word was God. (John 1:1 NASB)
He comes out of our mouth
And Balaam said to Balak, “Look, I have come to you! Now, have I any power at all to say anything? The word that God puts in my mouth, that I must speak.” (Numbers 22:38 NKJV)
Then the woman said to Elijah, “Now by this I know that you are a man of God, and that the word of the LORD in your mouth is the truth.” (1 Kings 17:24)
“But when I speak with you, I will open your mouth, and you shall say to them, ‘Thus says the Lord GOD.' He who hears, let him hear; and he who refuses, let him refuse; for they are a rebellious house. (Ezekiel 3:27 NKJV)
He really really came out of the mouth of Jesus
I will raise up a prophet from among their countrymen like you, and I will put My words in his mouth, and he shall speak to them all that I command him. (Deuteronomy 18:18 NASB)
Remember reading about the repentance of the son of man?
This does not mean that Jesus had reason to repent. Indeed what came out of the mouth of Jesus those where "God's words".
Jesus helps to make this clear to us
It is not what enters into the mouth that defiles the man, but what proceeds out of the mouth, this defiles the man." (Matthew 15:11 NASB)
James offers help to show what Jesus describes
With it we bless our Lord and Father, and with it we curse men, who have been made in the likeness of God; 10 from the same mouth come both blessing and cursing. My brethren, these things ought not to be this way. 11 Does a fountain send out from the same opening both fresh and bitter water? 12 Can a fig tree, my brethren, produce olives, or a vine produce figs? Nor can salt water produce fresh. (James 3:9-12 NASB)
The concept of the son of man defined into two types
- Fresh Water / Salt Water
- Good Tree / Bad Tree
One type causes curses. One type causes blessings.
Jesus expands on this concept using a tree metaphor
So every good tree bears good fruit, but the bad tree bears bad fruit. 18 A good tree cannot produce bad fruit, nor can a bad tree produce good fruit. 19 Every tree that does not bear good fruit is cut down and thrown into the fire. 20 So then, you will know them by their fruits. (Matthew 7:17-20 NASB)
Even John the Baptist explains this concept
Therefore bear fruit in keeping with repentance; 9 and do not suppose that you can say to yourselves, 'We have Abraham for our father'; for I say to you that from these stones God is able to raise up children to Abraham. 10 The axe is already laid at the root of the trees; therefore every tree that does not bear good fruit is cut down and thrown into the fire. (Matthew 3:8-10 NASB)
The blind man could "see" that the trees define people
And he looked up and said, “I see men, for I see them like trees, walking around.” (Mark 8:24 NSAB)
A quick summary of these classifications this far
A person can say good things or bad things. People who say bad things "cut down and thrown into the fire". We should repent(turn away) from saying bad things. Saying bad things defiles a person. We bear good fruit when we keep to repentance (aka: not saying bad things)
Jesus explains what our conversations should be like
But let your statement be, 'Yes, yes' or 'No, no'; anything beyond these is of evil. (Matthew 5:37 NASB)
But when they hand you over, do not worry about how or what you are to say; for it will be given you in that hour what you are to say. 20 For it is not you who speak, but it is the Spirit of your Father who speaks in you. (Matthew 10:19-20 NASB)
Good fruit just got defined as the Spirit of your Father who speaks in you.
Why no more need for Rules
After learning both good and evil from our parents, the law came to guide all to good, but who followed the Law or did all follow the law, or does all follow the law even this day?
Therefore instead of speaking about the evil of the day, and producing bad fruit that results in death, we bind up the evil inside of our bodies and do not set it free. This means resisting the urge to tell others about how sally did this wrong etc. etc.
For indeed if one does allow the words about evil to escape the lips, it comes back and the final condition of the one who spoke it.
The Truth of the Confession of Sin
Do not let your mouth cause your flesh to sin, nor say before the messenger of God that it was an error. Why should God be angry at your excuse and destroy the work of your hands? (Ecc 5:6 NKJV)
Sin does not mean Error
If you do well, will not your countenance be lifted up? And if you do not do well, sin is crouching at the door; and its desire is for you, but you must master it.” (Genesis 4:7 NASB)
- Saying what was done wrong kills the one who speaks it.
The real question a person should ask.
What is Sin that when I should confess I get forgiven and be given everlasting life?"
The short answer: Sin = Hate
The long answer concerning the definition of sin he will give to another question.