Why do we use Pastors instead of Psychologist, Psychiatrist, or certified counselors?
Pastors are called to lead the sheep. And their life's work is to understand God's word and instruct or counsel based on Biblical Doctrine and not their own theory or opinion. Jeremiah 3:15 "and I will give you pastors according to mine heart, which shall feed you with knowledge and understanding."
The qualifications for a Pastor can be found in
1 Timothy 3:1-14 and Titus 1:7-9.