This is a continuation from my previous post where I quote Matthew Henry's commentary on Matthew 5:28-30. The issue at hand is that I referenced was the weakened view of the sinfulness of sin by some in our Evangelical circles, perhaps in an effort to appear more compassionate in the public debates, especially with regard to sexual sin.
One of the dividing points is the distinction between the believer's experience of indwelling sin which still causes temptation and their willful acting out of particular behaviors. Generally speaking, the distinction made is that indwelling sin is not culpable (eg. merely one of the outcomes of the fall and just happens to people, like getting cancer). Historically, Protestants (especially of the reformed persuasion) have not held this view and I do not believe this view is based on scripture.
John Calvin, as one example, speaks rather clearly on these matters in several places in "The Institutes of Christian Religion". Here is an excerpt to that end:
"It may be alleged that human laws have respect to intentions and wishes, and not fortuitous events. .. They consider the animus with which the act was done, but they do not scrutinise the secret thoughts. Accordingly, their demand is satisfied when the hand merely refrains from transgression. On the contrary, the law of heaven being enacted for our minds, the first thing necessary to a due observance of the Law is to put them under restraint. But the generality of men, even while they are most anxious to conceal their disregard of the Law, only frame their hands and feet and other parts of their body to some kind of observance, but in the meanwhile keep the heart utterly estranged from everything like obedience. They think it enough to have carefully concealed from man what they are doing in the sight of God... Here the principal thing which the Law requires is wanting. Whence then, this gross stupidity, but just because they lose sight of the Lawgiver, and form an idea of righteousness in accordance with their own disposition? Against this Paul strenuously protests, when he declares that the "law is spiritual" (Rom. 7:14); intimating that it not only demands the homage of the soul, and mind, and will, but requires an angelic purity, which, purified from all filthiness of the flesh, savours only of the Spirit." - The Institutes of Christian Religion, Book II, Ch. 8 para.6.
Additionally, Calvin's commentary on Matthew 5:28-30 is exceptionally informative, as well:
27. You have heard that it was said to the ancients, Thou shalt not commit adultery. 28. But I say to you, That whoever shall look upon a woman to lust after her, hath already committed adultery with her in his heart. 29. And if thy right eye shall be a stumbling block405 to thee, pluck it out, and cast it from thee: for it is better for thee that one of thy members perish, and that thy whole body be not thrown into hell. 30. And if thy right hand shall be a hindrance to thee, cut it off, and cast it from thee: for it is better that one of thy members perish, and that thy whole body be not thrown into hell.
Matthew 5:27. Thou shalt not commit adultery. Christ proceeds with his subject, and shows, that the law of God not only has authority over the life, in a political view, to form the outward manners, but that it requires pure and holy affections of the heart. We must remember what I have already stated, that though Christ quotes the very words of the law, it is the gross and false meaning, which had been put upon it by dishonest interpreters, that he blames. He has already told us, that he did not come as a new Legislator, but as the faithful expounder of a law which had been already given. It might be objected that, through long practice, that interpretation had grown old. Christ expressly admits this, but meets it by saying, that the antiquity of an error ought not to be allowed to plead in its favor.
28. Whoever shall look upon a woman. The design of Christ was to condemn generally the lust of the flesh. He says, that not only those who have seduced their neighbors’ wives, but those who have polluted their eyes by an immodest look, are adulterers before God. This is a synec-doche:406 for not only the eyes, but even the concealed flames of the heart, render men guilty of adultery. Accordingly, Paul makes chastity (1 Corinthians 7:34) to consist both in body and in mind. But Christ reckoned it enough to refute the gross mistake which was prevalent: for they thought that it was only necessary to guard against outward adultery. As it is generally by the wantonness of the eyes that temptations are presented to the mind, and as lust enters, as it were, by that door, Christ used this mode of speaking, when he wished to condemn lust: which is evident from the expression, to lust after her.This teaches us also, that not only those who form a deliberate purpose of fornication, but those who admit any polluted thoughts, are reckoned adulterers before God. The hypocrisy of the Papists, therefore, is too gross and stupid, when they affirm that lust is not a sin, until it gain the full consent of the heart. But we need not wonder, that they make sin to be so small a matter: for those who ascribe righteousness to the merit of works must be very dull and stupid in judging of their sins.
29. If thy right eye shall be a stumbling-block to thee. It might be thought that, considering the weakness of the flesh and of nature, Christ pressed too severely on men, and therefore he anticipates all such complaints. The general meaning is, that however difficult, or severe, or troublesome, or harsh, any commandment of God may be, yet no excuse ought to be pleaded on those grounds, because the justice of God ought to stand higher in our estimation, than all that we reckon most precious and valuable. “You have no right to object to me, that you can scarcely turn your eyes in any direction, without being suddenly drawn away by some temptation: for you ought rather to part with your eyes, than to depart from the commandments of God.” And yet Christ does not mean, that we must mutilate our body, in order to obey God: but as all would readily wish, that they should not be restrained from the free use of their senses, Christ employs an exaggerated form of speech to show, that whatever hinders us from yielding that obedience to God which he requires in his law, ought to be cut off. And he does so expressly, because men allow themselves too much liberty in that respect. If the mind were pure, the eyes and hands would be obedient to it; for it is certain, that they have no movement of their own. But here we are deeply to blame. We are so far from being as careful as we ought to be, to avoid allurements, that we rather provoke our senses to wickedness by allowing them unbounded liberty.