Sin impacts thinking. Eph 4:18 claims that the unbeliever is darkened, not just the unbeliever but all humanity is affected by sin and corrupts our thinking. Common grace gives all humankind the ability to know true things, but not all that is claimed by an unbeliever is correct. The area that unbelievers and secular psychologists are most in error is in relating to God.
It is possible for secular psychologists to know facts, but they are unable to know the most important facts (Rom 1:18-23). A secular psychologist that gets closer God and His purpose for humankind the more pronounced the noetic effect is.
Humans are interpretive beings. Even though secular scientists can see, study and learn facts they interpret it through a secular framework. This is why it is important to examine the evidence presented and interpret it according to the Bible. While there is much to learn from secular psychologists, care should be taken in the acceptance of all their conclusions.
Heath Lambert writes that secular psychologists have three levels of information available to them: observations, interpretations, and interventions.
Observations come from careful study of the person and life in general. God’s common grace allows believers and unbelievers to know all manner of things. These observations are often compiled over many years. Depending on the level and type of area studied this can be some of the least effected by the noetic effect on human understanding. It is impossible to be absolutely certain if these observations are correct since they are still affected by the noetic effect of sin. Since humans are interpretive beings, they add meaning to what they observe they are not impartial observers.
When information is observed psychologists seek to understand that information. This information gathered is then interpreted. Science moves from observation to interpretation. Observations are never un-interpreted, no matter how careful the scientist. When a secular psychologist makes observations and interpretations they do so apart from knowledge and trust in God. This knowledge and trust in God are the most important part of any human and is indispensable in the counseling process. These interpretations have drastic effects for the person being counseled.
Interventions are the area where psychologists attempt to use the interpreted observations to develop therapies to help the person being counseled. Christians should be suspicious of therapies derived from these secular ideas and observations. Worldview has an impact on everything observed and interpreted. Christians should recognize the danger of using a distorted worldview to counsel. The information gathered should help biblical counselors in their efforts to help those in their care such as medical observations since humans have a body and a soul. However, healing must go beyond just the body. Biblical truth should always be a priority over that of secular psychologies. The Bible is the standard for truth and should be recognized as such.