Thou art a teacher of Israel. As Christ sees that he is spending his time and pains to no purpose in teaching so proud a man, he begins to reprove him sharply. And certainly such persons will never make any progress, until the wicked confidence, with which they are puffed up, be removed. This is, very properly, placed first in order; for in the very matter in which he chiefly plumes himself on his acuteness and sagacity, Christ censures his ignorance. He thought, that not to admit a thing to be possible would be considered a proof of gravity and intelligence, because that man is accounted foolishly credulous who assents to what is told him by another, before he has fully inquired into the reason. But still Nicodemus, with all his magisterial haughtiness, exposes himself to ridicule by more than childish hesitation about the first principles. Such hesitation, certainly, is base and shameful. For what religion have we, what knowledge of God, what rule of living well, what hope of eternal life, if we do not believe that man is renewed by the Spirit of God? There is an emphasis, therefore, in the word these; for since Scripture frequently repeats this part of doctrine, it ought not to be unknown even to the lowest class of beginners. It is utterly beyond endurance that any man should be ignorant and unskilled in it, who professes to be a teacher in the Church of God.

A master of Israel - A "teacher" of Israel; the same word that in the second verse is translated "teacher." As such a teacher he ought to have understood this doctrine. It was not new," but was clearly taught in the Old Testament. See particularly Psalm 51:10, Psalm 51:16-17; Ezekiel 11:19; Ezekiel 36:26. It may seem surprising that a man whose business it was to teach the people should be a stranger to so plain and important a doctrine; but when worldly-minded men are placed in offices of religion when they seek those offices for the sake of ease or reputation, it is no wonder that they are strangers to the plain truths of the Bible; and there have been many, and there are still, who are in the ministry itself, to whom the plainest doctrines of the gospel are obscure. No man can understand the Bible fully unless he is a humble Christian, and the easiest way to comprehend the truths of religion is to give the heart to God and live to his glory. A child thus may have more real knowledge of the way of salvation than many who are pretended masters and teachers of Israel, John 7:17; Matthew 11:25; Psalm 8:2, compared with Matthew 21:16.
Of Israel - Of the Jews; of the Jewish nation.

Art thou a master of Israel, etc. - Hast thou taken upon thee to guide the blind into the way of truth; and yet knowest not that truth thyself? Dost thou command proselytes to be baptized with water, as an emblem of a new birth; and art thou unacquainted with the cause, necessity, nature, and effects of that new birth? How many masters are there still in Israel who are in this respect deplorably ignorant; and, strange to tell, publish their ignorance and folly in the sight of the sun, by writing and speaking against the thing itself! It is strange that such people cannot keep their own secret.
"But water baptism is this new birth." No. Jesus tells you, a man must be born of water and the Spirit; and the water, and its effects upon the body, differ as much from this Spirit, which it is intended to represent, and the effects produced in the soul, as real fire does from painted flame.
"But I am taught to believe that this baptism is regeneration." Then you are taught to believe a falsity. The Church of England, in which perhaps you are a teacher or a member, asks the following questions, and returns the subjoined answers.
"Q. How many sacraments hath Christ ordained in his Church?"
"A. Two only, as generally necessary to salvation, that is to say, baptism and the supper of the Lord."
"Q. How many parts are there in a sacrament?"
"A. Two. The outward visible sign, and the inward spiritual grace."
"Q. What is the outward visible sign, or form, in baptism?"
"A. Water, wherein the person is baptized, In the name of the Father, and of the Son, and of the Holy Ghost."
"Q. What is the inward and spiritual grace?"
"A. A death unto sin, and a new birth unto righteousness; for being by nature born in sin, and the children of wrath, we are hereby made the children of grace."
Now, I ask, Whereby are such persons made the children of grace? Not by the water, but by the death unto sin, and the new birth unto righteousness: i.e. through the agency of the Holy Ghost, sin is destroyed, and the soul filled with holiness.

Jesus answered and said unto him,.... Upbraiding him with his continued and invincible ignorance, which was aggravated by his dignified character:
art thou a master in Israel? or "of Israel", as all the Oriental versions render it, as it literally may be rendered he was one of the , "wise men", or "doctors of Israel" (r), so often mentioned by the Jews. One of the Jewish doctors was answered, by a boy, just in such language as is here used; who, not understanding the direction he gave him about the way into the city, said to him, , "art thou he, a doctor", or "master of Israel?" did not I say to thee so? &c. (s). He was not a common teacher; not a teacher of babes, nor a teacher in their synagogues, or in their "Midrashim", or divinity schools, but in their great sanhedrim; and the article before the word used will admit it to be rendered, "that master", doctor, or teacher; that famous, and most excellent one, who was talked of all over Jerusalem and Judea, as a surpassing one: and now, though he was not only an Israelite, with whom were the laws, statutes, judgments, and oracles of God, the writings of Moses, and the prophets; but a teacher of Israelites, and in the highest class of teachers, and of the greatest fame among them, yet was he ignorant of the first and most important things in religion:
and knowest not these things? which were so plainly to be suggested in the sacred writings, with which he was; or ought to have been conversant: for the same things Christ had been speaking of, are there expressed by a circumcision of the heart; by a birth, a nation's being born at once; by sanctification; by the grace of God signified under the metaphor of water; and by quickening persons, comparable to dry bones, through the wind blowing, and breathing into them, Deuteronomy 30:6.
(r) Derech Eretz, fol. 18. 1. (s) Echa Rabbati, fol. 44. 4.

master--"teacher." The question clearly implies that the doctrine of regeneration is so far disclosed in the Old Testament that Nicodemus was culpable in being ignorant of it. Nor is it merely as something that should be experienced under the Gospel that the Old Testament holds it forth--as many distinguished critics allege, denying that there was any such thing as regeneration before Christ. For our Lord's proposition is universal, that no fallen man is or can be spiritual without a regenerating operation of the Holy Ghost, and the necessity of a spiritual obedience under whatever name, in opposition to mere mechanical services, is proclaimed throughout all the Old Testament.

Art thou a master of Israel, and knowest not these things? The question implies that Nicodemus was one of the doctors of the law. These made very arrogant claims of superior knowledge.