Materialism is the belief that matter is the only thing that exists and that all things can be reduced to matter (and energy since matter is a form of energy). Therefore, materialism would state that all things in the universe, including mankind, are necessarily restricted to operate within the bounds of physical laws. The human mind would cease to exist upon death because the physical brain ceases to function. Materialism would deny the continuation of the mind after death and would also deny any and all miracles.
Of course, materialism is unbiblical since the Bible tells us that God exists (Isaiah 43:10, 44:6, 45:5) and that the universe had a beginning (Gen. 1:1-31) and that we continue on after death (2 Cor. 5:8).
Problems with materialism
If all things are reducible to matter and all things must work under the boundaries of natural laws, then we are nothing more than the product of neural-chemical reactions that occur in the physical brain. This would negate the idea of real freedom and necessitate that our beliefs, thoughts, "free will," etc., are nothing more than the product of physical laws. Materialists counter by saying that the human free will and consciousness are emerging properties of supercomplex structures such as the brain. But, this is only a theory that must necessarily be assumed if one holds to materialism.
Furthermore, materialism itself is a concept. But how do concepts have any actual existence in a material world? The concept itself is not made up of physical parts or components. Therefore, since materialism says that all things that exist do so in the physical realm, the fact that concepts exist refutes that idea.
If the human mind is produced from arrangements of complexity of matter, then is it not logical to conclude that greater complexities of matter could also produce something you would call God that would exceed physical limitations? It would certainly seem so.