Like all evolutionists, Darwin had to assume the
truth of the Bible in order to argue against the truth
of the Bible.
Evolutionists often attempt to use observational
science—arguments from biology, paleontology,
geology, or even astronomy—to support their
belief. But the really interesting thing is that they
base all their arguments on principles that
ultimately come from biblical creation! As strange
as it may sound, evolutionists must unwittingly
assume that creation is true in order to argue
against it. That means that Darwin was (in a sense)
a “creationist.” All evolutionists must borrow the
principles of biblical creation in order to do science
(even though they would deny this). Here is why.

The Bible Provides the Foundation
for an Orderly Universe

To do science, certain things must be true. The
universe must be logical and have some
organization to it. Moreover, the human mind must
be capable of rational thought—capable of
considering the various alternatives and then
choosing the best. But if evolution were true, then
we would have no reason to expect either of these
conditions. If this world were nothing but a cosmic
accident, if our brains were nothing but rearranged
pond scum, then why would they be able to
understand the universe?
On the other hand, a biblical creationist has every
reason to expect scientific inquiry to be possible.
The Bible teaches that God made the universe and
the human mind, so we would expect these two
things to “go together.” Moreover, since God gave
Adam the responsibility to care for creation, it
makes sense that He would have given Adam the
ability to understand the natural world.

The Bible Is the Foundation for
Logic

Logical reasoning itself only makes sense in a
biblical worldview. To make a logical argument
about anything, we have to use laws of logic. But if
the universe is just matter in motion (as many
evolutionists believe), laws of logic wouldn’t exist
since laws of logic are not made of matter. Laws of
logic are “rules” that help us distinguish correct
from incorrect forms of reasoning. But in an
evolutionary universe, why should there be a
standard for reasoning, and who is to say what that
standard is? How could we ever really know for
certain the laws of logic?
In the biblical creation worldview, however, laws of
logic make sense. They reflect the thinking of God
who upholds the entire universe by His power. God
is our standard for correct thinking because all
truth is in Him. We can know about laws of logic
because God has made us in His image and has
revealed some of His thoughts to us in His Word.
We can expect laws of logic to be universally true
and never change because they stem from the
nature of God. So, when evolutionists such as
Charles Darwin attempt to use science and logic,
they reveal the fact that in their heart of hearts they
know the God of creation.

The Bible Makes Sense of Rules of
Behavior

Additionally, evolutionists believe in a moral code: a
standard for how we should think and behave. But
the idea of a moral code goes back to biblical
creation. Since God has created us, He has the right
to set the rules of behavior. In fact, the Bible tells us
that the law is written on our hearts. However, if
people were just complex chemicals and our
decisions were just chemical reactions, then people
wouldn’t have any genuine choice in what they do. If
we were not created by God, then any moral code
invented by people would just be arbitrary opinion.
This doesn’t mean that evolutionists don’t act
morally, but those who reject biblical creation have
no ultimate basis for their morality. So when
evolutionists tell us how to think or behave, they are
acting as if they believe in creation. Their actions
reveal that they embrace an objective moral code,
even though they have no basis for it in their
professed worldview.
The fact that evolutionists believe in science,
rationality, and morality is inconsistent with their
professed belief in evolution. This shows that in
their hearts, they really know the God whose Word
they are attacking, even though they verbally deny
this. They “suppress” the truth, as the Scripture
teaches (Romans 1:18–25).

From Darwin to Dawkins, all evolutionists have
relied upon their suppressed knowledge of the God
of creation—as evidenced by their belief in science,
logic, and morality. As a result of their failure to
honor God or thank Him, their thinking is reduced
to futile speculations (Romans 1:21).
The notion of particles-to-people evolution is just
one example of mankind’s speculations. But people
cannot consistently function rationally with such a
futile way of thinking. In their effort to construct
arguments against biblical creation, evolutionists
must unwittingly rely on the concepts that can come
only from biblical creation.
All knowledge is in Christ (Colossians 2:3). So
anyone who wants to be consistently rational and
scientific must submit to Him first (Proverbs 1:7).
Christians who understand and embrace this truth
have a powerful tool for defending the Christian
faith and reaching the unsaved with the gospel.
The next time someone tries to condemn the
biblical view of origins using arguments from
biology or other sciences, just remind him that
scientific arguments make consistent, logical sense
only when reality is understood from a biblical
worldview, beginning with creation. Equipped with
this powerful apologetics method, you can point out
how all evolutionists must, in reality, assume that
creation is true in order to attempt to logically
argue against it.
Beginning your discussions on the Scripture’s
authority, you will stand on solid ground (Matthew
7:24–29).

https://answersingenesis.org/charles-darwin/darwin-unwittingly-a-creationist/