Are you gonna split hairs?
Since the first time I heard it, I've taken umbrage with the assertion that Jesus "says it's the same" when a person looks with lust as committing adultery.
Then and now, I say, that's NOT what the text says, nor what it means.
“You have heard that it was said, ‘You shall not commit adultery.’ But I say to you that everyone who looks at a woman with lustful intent has already committed adultery with her in his heart. (Matthew 5:27-28, ESV)
What it says and means is that external obedience is not enough, God is concerned with the heart of a person. So, while a person may look okay on the outside, the inside of the cup is dirty and there's culpability to God. The context and Jesus many dealings with the Pharisees bears that out.
In other words, "You're not off the hook; you've committed a sin of the heart."
Some may think I'm quibbling, but a growing trend has me concerned about the practical ramifications of equating lust and adultery.
Some see adultery as a legitimate reason for a spouse to divorce and then remarry another. With the preponderance of opportunities for a man to lust (commercials, billboards, scantily clad waitresses, etc.) it's highly unlikely a husband will go the length of his marriage without ever lusting after a woman not his wife.
So, does that mean his wife may divorce him? If you equate lust & adultery and you allow divorce in that scenario, then I don't see why not.
Crazy you say, but I heard of real life examples of wives using this as their way out of a marriage. That's not my primary reason for objecting to equating lust & adultery, but it certainly gives pause for consideration.
My response, however, in such a scenario would be to go back to the text and show that Jesus does not say that lust and adultery are "the same thing," even though both actions put one in the category of guilty before God who sees even the intents of the heart.