Christianity means that moral laws are breakable, but never without consequences. That makes them more like physics.
Every moral failing results in an opposite and equal reaction.
Discussion
the distinction that would make it clearer to her is the latency of the consequences
some things take a long time to circle back and bite you
Yes, Christians believe it might take until the end of the world, but it will then bite you.
the end of the world is probably only 12000 years in total though, so there's that also
yikes! so how much of following of the law should be driven by fear of consequences vs just being a better person? it feels like it's impossible to not fall into a useless obsession with following laws that's completely unhelpful to moral development. so then it's easy to make up excuses for why certain laws just don't apply anymore.
i'm always looking for excuses for why i can be pagan and christian at the same time...