In my ministry in London I often used to say that what determines whether or not you and I are Christians is not what we say on vacation and not what we say when we are in our studies or reading a book somewhere and reading about theology and reading the Scriptures. This is not the ultimate test.
The ultimate test of our profession of the Christian faith is what we feel, what we say, and what our reaction is when a hurricane comes or a tornado or some calamity produced by nature or some violent epidemic, a disease that brings us face-to-face with time and eternity, with life and death. The ultimate question is, what is our response then?
From Martyn Lloyd-Jones, Setting Our Affections Upon Glory