I suggest that there are three tests to which any system or statement that makes a claim to truth must be subjected as a preliminary requirement if that statement is to be considered meaningful for debate. Those tests are (1) logical consistency, (2) empirical adequacy, and (3) experiential relevance.
These three tests provide a high degree of confidence that as they are applied to a system of belief, truth or falsehood can be established. The truth claims of Christianity, Hinduism, Buddhism, Islam or atheism must all meet these tests. Is there a logical consistency in what is stated? Is there empirical adequacy where its truth claims can be tested? Is there experiential relevance – does it apply meaningfully to my life?
Ravi Zacharias, Can Man Live Without God?, p 123-124