Depends upon your goal. The Reformers had a concept of "civil righteousness." Not saving, but good for society. There are plenty of areas where Christians and non-Christians can agree on good behavior. Those things should be encouraged. Jesus taught that we should care about everyone, and those behaviors promote general welfare.
Actually that's not so different from teaching morals to Christians. Salvation isn't based on morals for Christians either, so the major reason is that they're how God wants us to behave, and presumably God wants that in large part because it's good for those around us.
So moral behavior for Christians comes from our commitment to Christ, and for non-Christians doesn't, but still, the purpose is similar.