Ken Ham argues that science is split into two general types. Observational science, which is traditional science as practiced in the present using the scientific method, and historical science, which are any claims about the past that contradict the Bible. He claims historical science is baseless because we were not there to observe it so it cannot be true. The only source of scientific truth is the Bible.
Bill Nye argues that there is no such distinction between observational and historical science and that natural processes do not change simply because we were not there to observe them.
Major respect to Bill Nye for readily admitting that science cannot answer the origin of matter that was originally there in that pinprick of atoms that exploded with the Big Bang. Richard Dawkins, the atheist thinker, did not do that in his popular book The God Delusion.
Religious people are never going to be swayed with Bill Nye’s scientifically based arguments because Ken Ham cloaks his arguments with enough science to seem valid upon first exposure and then pulls on the Bible to provide a complete answer to why we exist.
It is brave, but ultimately unsatisfying to lay people, to admit that there are things we do not yet understand and that real scientific exploration is the only means we will ever have to discover these answers and that to be self-satisfied with religious scripture as the only answer to these essential human questions is a threat to real scientific work.
The only way to win a debate with a faith-based debater is to accept the premises of the faith-based debater and use their source of argumentation, the scripture, against them.
Bill Nye did not win this debate.