Some divorce religion into two analytical categories: On the one hand there are the observable, called inessential, parts, and following that, the mysterious and unseen inner faith at the heart of religion, the supposedly essential experience. Thus our culture’s idiotic maxim, “Spiritual, not religious,” is understood to possess meaning.
In response to this, I would be loath to prattle on some Bible verses, asking the speaker to show me their faith without their works, or some such challenge, because like most things people say regarding religion, it is a lie, or at least a euphemism. In my experience it has invariably meant, “I don’t believe what my parents taught me, but I still kind of do.” It is often the remark of a confused person who wants to change the subject. Generally, I do not challenge a person who says this, but will—baring any context which might stop me—simply share my faith, expressing what I believe and why.