In Matthew 5:27-30 Jesus affirms very unambiguously the sinfulness of lust:
27 “You have heard that it was said, ‘You shall not commit adultery.’ 28 But I say to you that everyone who looks at a woman with lustful intent has already committed adultery with her in his heart. 29 If your right eye causes you to sin, tear it out and throw it away. For it is better that you lose one of your members than that your whole body be thrown into hell. 30 And if your right hand causes you to sin, cut it off and throw it away. For it is better that you lose one of your members than that your whole body go into hell. (ESV)
However, if one asks the follow-up question "But what's wrong with having lustful thoughts?", a Divine Command Theory advocate might say "Well, lustful thoughts are evil because God has commanded that you shouldn't have them".
I'm not interested in that sort of answer here. That's why I'm scoping this question to Christians who do not adhere to Divine Command Theory.
If we assume that Divine Command Theory is false (for scoping purposes), what would be alternative ways within a Christian worldview to defend the claim that lust (of the kind that Jesus is describing in Matthew 5:27-30) is universally evil? What's wrong with lust without appealing to Divine Command Theory?
EDIT: Someone in the comments rightly pointed out that the word "evil" is not literally mentioned by Jesus anywhere in the passage I quoted. Instead, the literal word used is "sin". That's a fair observation. In the way I phrased the question I'm intuitively using "wrong", "evil" and "sinful" interchangeably, but for some Christians that might not be the case. Can something be sinful without being evil and vice versa? I leave the space to answerers to answer that question as they see fit, as long as they are coming from a Christian ethical viewpoint other than DCT.