Are you consistent? Let's play out this principle in your neighborhood:
Let's say you find out there are 5 sex offenders--all of whom have molested boys--living in your immediate neighborhood. But that's okay, you think; you also hear that your Christian neighbors are witnessing to them on an ongoing basis.
The homosexual community has tried to reduce the age of consent law for years. You hear that their lobbyists are on the verge of reducing the age of consent; but you take no action in this "culture war" activity because you've properly prioritized your spiritual agenda by joining your Christian neighbors in witnessing to these sex offenders. You witness to them all the while your son grows from age 10 to age 12, a year in which the homosexual lobby finally comes through and gets what it wants: The age of consent is now age 12.
A sex offender then coerces your son into a sexual activity which prior to that latest cultural skirmish would have been a criminal act. But you've got peace in your soul because, after all, what your son needed was not a proper age of consent law, for that did not address the sin problem of these sex offenders or your son, now did it?
Try on this Scripture for size: "If anyone causes one of these little ones--those who believe in me--to stumble, it would be better for them if a large millstone were hung around their neck and they were drowned in the depths of the sea. Woe to the world because of the things that cause people to stumble! Such things must come, but woe to the person through whom they come!" (Matt. 18:6-7)
Yeah, sin is alive and well, Jesus says. "Such things must come" and culture war or not, those things are a coming. But that doesn't preclude us as responsible citizens from prioritizing efforts that not only protect children but also reflect Jesus' obvious deep commitment to warding off those who would do them harm.
I don't even need to use hypotheticals to make this point. Most states do not have enforced parental consent laws that protect their minor daughters from getting abortions. Why? Because Christians take the attitude of "If a Christian girl is 'pressured' into having sex with her boyfriend, what she needs after becoming pregnant is not a parental consent law, for a parental consent law won't address her sin."
No? Then tell me why in Minnesota in the ensuing years after a parental consent law was passed there that the teen pregnancy rate went down in that state? (Teens are not as dumb as we take them to be; teen girls knew that minus the back-up of abortion availability, they would have to face Mom & Dad). And No? Even if it did nothing for the teen, it would certainly protect my grandchild or yours who happens to reside in her womb.
Law does have both a restraining and teaching effect, even if it doesn't ultimately change the heart. And a Christian-lit culture failing to pour Jesus' passion for little ones into laws protecting its young or doesn't culturally engage the millstone-draped, bottom-of-sea-bound folks are not serving as God's messengers.
We need to culturally intervene by risking our own lives as Lot did to protect those "who have come under the protection of my roof" (Gen. 19:8). And if criminals insist on criminal behavior, we need to pray for the same blindness to strike them so that they cannot prey upon their victims (Gen. 19:11). But I guess that's not very seeker-sensitive or evangelistic, is it? (I guess you can take that up with those two angelic messengers)
Your scenario of the sex offenders is not how I think. So, entertaining as it is, it is an extended straw man and a waste of time.