The Noetic Effect of Sin refers to the effect of sin after the fall in Genesis 3 on man’s ability to reason. This theological phrase roots itself in the Scripture in verses such as Romans 1:21 and 1 Corinthians 2:14. As sin entered the world through Adam, it corrupted every part of man. Everything from his physical being to his relationship to God was marred. It then follows, as we read in Romans 1:21, that man’s full ability to use our God given gift to reason is also affected by the corruption of sin. While most theologians agree on the doctrine of the Noetic Effect of Sin, many apologists differ on the extent of it.
As with all subjects of theology, two extremes can be found on the extent of the damage done by sin on the ability to reason. Presuppositional apologetics is a method of apologetics that focuses on the presupposition (basic assumption) that the Christian God is an axiomatic First Principle (meaning that God is like the laws of logic; you can’t scientifically prove Him, but like the laws of logic, you must assume His existence in order to make sense of the world) needed in to explain logic, science and morality. Furthermore, other worldviews must unknowingly presuppose our God to live their lives rationally and morally. Presuppositionalism is a very useful apologetic method that uses what is called the Transcendental Argument for God (article about this coming soon), to show that Christianity is the only true worldview. However, some Presuppositionalists, such as Cornelius Van Til, have been accused of exaggerating the Noetic Effect on human reason. Van Til would argue that there is simply no point in attempting to provide evidences for things such as the historicity of the resurrection of Jesus because the unbelieving mind would refuse any amount of evidence due of his fallen nature. There is no intellectual neutrality that would allow the unbeliever to look at the evidence unbiased and come to a reasoned conclusion about the resurrection of Jesus. To some, this an extreme view of the reasoning ability of the fallen man.
On the flip side of the coin, you have Evidential apologetics. Evidential apologetics start from the basis that the unbeliever can look at a body of evidence provided by the Christian, evaluate it, and come to a rational conclusion, even if that conclusion is in opposition against their worldview’s presuppositions. If we go to the extreme examples of the Evidentialist’s view of the Noetic Effect of Sin (again, not every Evidential apologist has this view of the Noetic Effect of Sin) such as Aquinas, who relied on Aristotelian, deductive argumentation. Aquinas (though it is slightly disputed), believed that man’s ability to reason their way to God through evidence was unhindered by sin, though there were things such as the Trinity that had to be divinely shown. This means that, in Aquinas’ view, there is an intellectual neutrality in the minds of unbelievers that allows them to follow the evidence of God wherever it may lead unimpeded. This view of the Noetic Effect would take the passage in Romans 1 as being an initial rejection of a belief in God, but not an active suppression caused by their fallen nature.
There are several other nuanced views of the Noetic Effect of Sin within Christendom. My own view lies somewhere in the middle of the two extremes. I do believe that the Noetic Effect of Sin on the minds of unbelievers will cause them to disregard evidences if the only variable at play is their own reasoning abilities. However, I also believe that if the doctrine of the Noetic Effect is true, then the Presuppositional apologist must come to grips that their method of apologetics is just as futile as the Evidentialist’s. I believe there is another variable that comes into play that can be forgotten within the debate that allows both methods of apologetics to be valid and useful in different circumstances; the Holy Spirit. When we are employing the use of apologetics, we are simply creating avenues to share the Gospel with the unbeliever. No matter how air tight our argumentation is, no matter which apologetic method we use, it is the Holy Spirit that convicts and brings about New Birth within the unbeliever. It is the work of the Holy Spirit that allows the mind of the unbeliever to accept the evidences of Christ. It is the Holy Spirit that allows the unbeliever to accept God as the First Principle from which all reality derives its meaning. Consequently, I believe that He can use whichever method He desires to bring people to repentance and faith.
It is important to note that I do not believe there are many who take such extreme views of the Noetic Effect of Sin. I also do not believe that most Christians who use either method of apologetics down play the role of the Holy Spirit. For the sake of the conversation, it can be helpful to look at extremes to fully grasp the concept of a doctrine. Regardless, no matter the extent of the Noetic Effect of Sin, God is simply greater.