Is it worth debating with Christians?

Yes.

It is worthwhile debating with people who have different views to ourselves for a number of reasons.

1) In an open democratic society the free exchange of ideas is a viable part of any social dialogue.

2) When an idea is put forward it is important for it to be debated and discussed so that it can be examined from many angles.

3) Debates do not normally sway the views of the participants so much as they influence the listeners.

4) Public debate draws attention to issues.

5) It shows that the Christian view of the world is not accepted as valid by all.

Rational discussion of any issue does make a difference to public perception of the issue and it's related issues.