Conviction is no sure evidence - Boston

The well known Christian author Thomas Boston (here) wrote (emphasis mine)

"A person may have sharp soul-exercises and pangs, and yet die in the birth. Many "have been in pain," that have but, "as it were, brought forth wind." There may be sore pangs of conscience, which turn to nothing at last. Pharaoh and Simon Magus had such convictions, as made them to desire the prayers of others for them. Judas repented: and, under terrors of conscience, gave back his ill-gotten pieces of silver. All is not gold that glitters. Trees may blossom fairly in the spring, on which no fruit is to be found in the harvest: and some have sharp soul-exercises, which are nothing but foretastes of hell.

Some have sharp convictions for a while: but these go off, and they become as careless about their salvation, and as profane as ever, and usually worse than ever; "their last state is worse than their first," Matt. 12:45. They get awakening grace—but not converting grace; and that goes off by degrees, as the light of the declining day, until it issues in midnight darkness.

There may be a wonderful moving of the affections in souls that are not at all touched with regenerating grace. When there is no grace, there may, notwithstanding, be a flood of tears, as in Esau, who "found no place of repentance, though he sought it carefully with tears," Heb. 12:17. There may be great flashes of joy; as in the hearers of the word, represented in the parable of the stony ground, who "with joy receive it," Matt. 13:20. There may be also great desires after good things, and great delight in them too; as in those hypocrites described in Isa. 58:2, "Yet they seek me daily, and delight to know my ways – they take delight in approaching to God."

Common operations of the divine Spirit, like a land-flood, make a strange turning of things upside down: but when they are over, all runs again in the ordinary channel. All these things may be, where the sanctifying Spirit of Christ never rests upon the soul—but the stony heart still remains; and in that case these affections cannot but wither, because they have no root."

These are my views exactly and the views of the genuine old Baptists. Hardshells, being quasi universalists, find conviction of sin, even in the above named wicked characters, to be an evidence of "regeneration." A dangerous teaching is this.