In many cases they simply lack sufficient education (i.e., reading knowledge) in
the subject matter. The modern disconnection of empirical laboratory science
from the philosophical and theoretical background of its origins is a modern
innovation. And part of the legacy of intellectual mediocrity which characterizes
liberal secular humanism.
The history of philosophy is usually not even taught in high school. And when it is
taught in college these days it is usually done very poorly. The result is a complete
lack of awareness of logical and theoretical concepts, where they come from,
what they can and cannot demonstrate regarding ultimate claims. There is no sound logical basis for the primary theoretical assumptions and metaphysical
conclusions of scientific materialism (i.e., atheistic scientism). It is built on
emotion, anti-Christian bias, and a lot of hot air (to be blunt about it).
Hence, some of the ridiculously absurd, contradictory, and emotional statements
about intelligent design coming from wacko liberal secular humanists. If they are
really that afraid of Jesus, they might want to see someone (like a psychiatrist or psychologist) to talk through these feelings.