Question

What are the reasons one should believe in Reformed Christianity as put forth by the OPC as opposed to some form of atheistic materialism?

Answer

Your question is interesting. You seem to be asking why we should believe in a sovereign God as opposed to not believing in any god at all because the only things that are real are those things we can know by our senses—by touch, taste, sight, smell or hearing. This is classic atheism at its finest, or more properly, at its worst. It holds that since God is not accessible to the senses, not only is it impossible to be certain he exists but it is impossible that he does, for all that really exists is that which consists of matter.

The theory fails for want of comprehensive knowledge. The materialist assumes, or presupposes, that what is not matter cannot exist—what you cannot see or taste or feel or hear or smell does not exist. But how does the materialist know? He assumes infinite and comprehensive knowledge, something no human being has.

The theory also fails due to inconsistency. Do thoughts exist? Thoughts about materialism exist? They are not available to the senses because they are not made up of matter. Logic dictates we deny the existence of thoughts if they cannot be tasted, felt, heard or smelled.

Materialism finally falls under the withering words of Paul in Romans 1:18–23,

For the wrath of God is revealed from heaven against all ungodliness and unrighteousness of men, who by their unrighteousness suppress the truth. For what can be known about God is plain to them, because God has shown it to them. For his invisible attributes, namely, his eternal power and divine nature, have been clearly perceived, ever since the creation of the world, in the things that have been made. So they are without excuse. For although they knew God, they did not honor him as God or give thanks to him, but they became futile in their thinking, and their foolish hearts were darkened. Claiming to be wise, they became fools, and exchanged the glory of the immortal God for images resembling mortal man and birds and animals and creeping things.

The materialist is really a person who suppresses the truth of what he/she knows about God.

The only alternative is to acknowledge what each human being knows in his heart—the existence of the Creator who sovereignly created all things by the word of his power. That is the Reformed view as held by the OPC.

I hope this answers your question.