At first glance, this is a good sign for a Christian. After all, Jesus replaces “an eye for an eye” with “Do not resist the one who is evil” (Matthew 5:38-39).
But I think it illustrates the way we fail to understand certain phrases as they were intended.
“An eye for an eye” or lex talionis was originally also a way to keep the whole world from going blind. It was intended not to mandate revenge, but to limit it. Modern Christians understand it as some sort of command to mass mayhem, and are thankful that Jesus overruled it.
But in fact Jesus simply moved us further along the same path. Limiting revenge was good. Forgiveness was even better, though in justice we still find some value in the idea of proportional penalties.
This sign demonstrates a quite frequent response to the Old Testament, and in many cases to other things that are old. In seeing the New Testament as good, these Christians have to see the Old Testament as bad. It is almost as though there was no grace for thousands of years and then suddenly at the appearance of Jesus God’s grace came into being.
But in fact the grace that Jesus taught was also taught in the Old Tesament, with the teaching accommodated to time and place.
So yes, I think Jesus improved on the attitude of “an eye for an eye.” But “an eye for an eye” was, in its time and place, also a forward looking measure of justice.