As a practicing Catholic who is also a practicing scientist, I find these kinds of questions silly. Only people who are using science as a religion pose such questions.
Here’s what I might say: Science is a tool for helping us to understand the physical world. However it is not the only tool. There is more to life than rational explanations of the world. Science does not answer teleologic (why?) questions. It also does not tell you what is moral, regardless of what people like Carl Sagan implied in the past.
There is an aspect of this world which is fundamentally mysterious and science does not touch this. Ask them if they love their wife, etc. What does that love mean from a scientific standpoint? Nothing, because it is outside the scope of scientific inquiry. So I would say that science is a limited tool and the world will always be mysterious, no matter how far we go in our explanations.
You might run into an reductionist materialist who answers that love is just a biochemical reaction going on in their minds and hence not relevant. This is another silly idea. Ask them, if that is true, then is the scientific method just a biochemical reaction? If so, why give it any credence?
Another point of attack with such people is to emphasize the importance of faith. Even scientists have to take things on faith, such as the scientific results of previous workers. If we didn’t , we’d never get to the job at hand; we’d just have to re-prove what everyone else has done.
In calling things silly above, I didn’t mean to belittle you. It annoys me to see people have such misconceptions about science. Help these people see the larger world they are in!
Best of luck!