{2} But when he saw many of the Pharisees and Sadducees come to his baptism, he said unto them, O generation of vipers, who hath warned you to flee from the wrath to come?

(2) There is nothing that shuts up the way of mercy and salvation from us so much as the opinion of our own righteousness does.

People's New Testament

3:7 When he saw many of the Pharisees and Sadducees. The two principal religious sects. (1) The first originated in the time of the Maccabees, and were a kind of Jewish Puritans, but had in the Savior's time degenerated into a set of formalists, who paid far more attention to outward forms than to inner life. They were scrupulous in observing ceremonies, very orthodox, but were filled with spiritual pride. From an early period of Christ's ministry they opposed him. (2) The other principal sect of the Jews, the Sadducees, derived their name from Sadduc, the founder of the sect; were irreligious, sensual and skeptical. They were materialists, and denied angel, spirit, or the resurrection of the dead (Ac 23:8). Annas and Caiaphas, the high priests, were Sadducees.

Generation of vipers. The guilty corrupted race had become a generation of vipers; not only poisonous, hateful to God, hating one another. The viper is hateful, full of hate, and dangerous.

Who hath warned you? Malachi (Mal 3:2 4:5) had predicted the wrath to come. John's question expresses doubt of their sincerity.

Wesley's Notes

3:7 The Pharisees were a very ancient sect among the Jews. They took their name from a Hebrew word, which signifies to separate, because they separated themselves from all other men. They were outwardly strict observers of the law, fasted often, made long prayers, rigorously kept the Sabbath, and paid all tithe, even of mint, anise, and cummin. Hence they were in high esteem among the people. But inwardly, they were full of pride and hypocrisy. The Sadducees were another sect among the Jews, only not so considerable as the Pharisees. They denied the existence of angels, and the immortality of the soul, and by consequence the resurrection of the dead. Ye brood of vipers - In like manner, the crafty Herod is styled a fox, and persons of insidious, ravenous, profane, or sensual dispositions, are named respectively by him who saw their hearts, serpents, dogs, wolves, and swine; terms which are not the random language of passion, but a judicious designation of the persons meant by them. For it was fitting such men should be marked out, either for a caution to others, or a warning to themselves.

Scofield Reference Notes

[2] Pharisees

Song called from a Heb. word meaning "separate." After the ministry of the post-exilic prophets ceased, godly men called "Chasidim" (saints) arose who sought to keep alive reverence for the law amongst the descendants of the Jews who returned from the Babylonian captivity. This movement degenerated into the Pharisaism of our Lord's day--a letter-strictness which overlaid the law with traditional interpretations held to have been communicated by Jehovah to Moses as oral explanations of equal authority with the law itself. (cf. Mt 15.2,3 Mk 7.8-13 Gal 1.14).

The Pharisees were strictly a sect. A member was "chaber" (i.e. "knit together,") Jud 20:11 and took an obligation to remain true to the principles of Pharisaism. They were correct, moral, zealous, and self-denying, but self-righteous Lk 18:9 and destitute of the sense of sin and need Lk 7:39. They were the foremost prosecutors of Jesus Christ and the objects of His unsparing denunciation (e.g.) Mt 23:13-29 Lk 11:42,43

[3] Sadducees

Not strictly a sect, but rather those amongst the Jews who denied the existence of angels or other spirits, and all miracles, especially the resurrection. They were the religious rationalists of the time Mk 12:18-23 Acts 5:15-17 23:8 and strongly entrenched in the Sanhedrin and priesthood Acts 4:1 5:17. They are identified with no affirmative doctrine, but were mere deniers of the supernatural.

Jamieson-Fausset-Brown Bible Commentary

7. But when he saw many of the Pharisees and Sadducees come to his baptism, he said unto them-astonished at such a spectacle.

O generation of vipers-"Viper brood," expressing the deadly influence of both sects alike upon the community. Mutually and entirely antagonistic as were their religious principles and spirit, the stern prophet charges both alike with being the poisoners of the nation's religious principles. In Mt 12:34; 23:33, this strong language of the Baptist is anew applied by the faithful and true Witness to the Pharisees specifically-the only party that had zeal enough actively to diffuse this poison.

who hath warned you-given you the hint, as the idea is.

to flee from the wrath to come?-"What can have brought you hither?" John more than suspected it was not so much their own spiritual anxieties as the popularity of his movement that had drawn them thither. What an expression is this, "The wrath to come!" God's "wrath," in Scripture, is His righteous displeasure against sin, and consequently against all in whose skirts sin is found, arising out of the essential and eternal opposition of His nature to all moral evil. This is called "the coming wrath," not as being wholly future-for as a merited sentence it lies on the sinner already, and its effects, both inward and outward, are to some extent experienced even now-but because the impenitent sinner will not, until "the judgment of the great day," be concluded under it, will not have sentence publicly and irrevocably passed upon him, will not have it discharged upon him and experience its effects without mixture and without hope. In this view of it, it is a wrath wholly to come, as is implied in the noticeably different form of the expression employed by the apostle in 1Th 1:10. Not that even true penitents came to John's baptism with all these views of "the wrath to come." But what he says is that this was the real import of the step itself. In this view of it, how striking is the word he employs to express that step-fleeing from it-as of one who, beholding a tide of fiery wrath rolling rapidly towards him, sees in instant flight his only escape!

Matthew Henry's Concise Commentary

3:7-12 To make application to the souls of the hearers, is the life of preaching; so it was of John's preaching. The Pharisees laid their chief stress on outward observances, neglecting the weightier matters of the moral law, and the spiritual meaning of their legal ceremonies. Others of them were detestable hypocrites, making their pretences to holiness a cloak for iniquity. The Sadducees ran into the opposite extreme, denying the existence of spirits, and a future state. They were the scornful infidels of that time and country. There is a wrath to come. It is the great concern of every one to flee from that wrath. God, who delights not in our ruin, has warned us; he warns by the written word, by ministers, by conscience. And those are not worthy of the name of penitents, or their privileges, who say they are sorry for their sins, yet persist in them. It becomes penitents to be humble and low in their own eyes, to be thankful for the least mercy, patient under the greatest affliction, to be watchful against all appearances of sin, to abound in every duty, and to be charitable in judging others. Here is a word of caution, not to trust in outward privileges. There is a great deal which carnal hearts are apt to say within themselves, to put aside the convincing, commanding power of the word of God. Multitudes, by resting in the honours and mere advantages of their being members of an outward church, come short of heaven. Here is a word of terror to the careless and secure. Our corrupt hearts cannot be made to produce good fruit, unless the regenerating Spirit of Christ graft the good word of God upon them. And every tree, however high in gifts and honours, however green in outward professions and performances, if it bring not forth good fruit, the fruits meet for repentance, is hewn down and cast into the fire of God's wrath, the fittest place for barren trees: what else are they good for? If not fit for fruit, they are fit for fuel. John shows the design and intention of Christ's appearing, which they were now speedily to expect. No outward forms can make us clean. No ordinances, by whomsoever administered, or after whatever mode, can supply the want of the baptism of the Holy Ghost and of fire. The purifying and cleansing power of the Holy Spirit alone can produce that purity of heart, and those holy affections, which accompany salvation. It is Christ who baptizes with the Holy Ghost. This he did in the extraordinary gifts of the Spirit sent upon the apostles, Ac 2:4. This he does in the graces and comforts of the Spirit, given to those that ask him, Lu 11:13; Joh 7:38,39; see Ac 11:16. Observe here, the outward church is Christ's floor, Isa 21:10. True believers are as wheat, substantial, useful, and valuable; hypocrites are as chaff, light and empty, useless and worthless, carried about with every wind; these are mixed, good and bad, in the same outward communion. There is a day coming when the wheat and chaff shall be separated. The last judgment will be the distinguishing day, when saints and sinners shall be parted for ever. In heaven the saints are brought together, and no longer scattered; they are safe, and no longer exposed; separated from corrupt neighbours without, and corrupt affections within, and there is no chaff among them. Hell is the unquenchable fire, which will certainly be the portion and punishment of hypocrites and unbelievers. Here life and death, good and evil, are set before us: according as we now are in the field, we shall be then in the floor.