One of my favorite preachers and writer of all times is A.W. Tozer. A. W. Tozer's conversion to Christ at seventeen. As a result he gained an insatiable hunger and thirst for the things of God and became a great pastor of his time. Tozer had not attended Bible college or seminary, Tozer received two honorary doctorates.
Another person, my mentor, my good friend, my pastor who died of cancer September 10, 1999 at very young age didn't have college education. He was trained by a very respected spiritual local Church which was like a seminary. He was remembered by many that he loved his God, loved his family, and loved his people (Deaf people). His life verse was Jude 1:22, "And of some, having compassion, making a difference." Only eternity will tell how God has used his life and death to influence many Deaf and hearing people here and around the world.
For 3 years, Jesus taught His Disciples who became Apostles after His death. What kind of education did Jesus gave them? Reading all of the New Testament, I have come to conclusion that Jesus taught them Spiritual matters.
Teachers are to have good reputation. In the book of Titus, the requirements are: Show integrity, seriousness and soundness of speech that cannot be condemned, so that those who oppose they may be ashamed because those have nothing bad to say about them. That teachers are to say "No" to ungodliness and worldly passions, and to live self-controlled, upright and godly lives in this present age. In 2 Corinthians 7:2 says that we "make room for others in our hearts. We have wronged no one, we have corrupted no one, we have exploited no one." This is where "accountability" comes in. In 1 Timothy 3:1-3: If anyone sets his heart on being an overseer, he desires a noble task. Now the overseer must be above reproach, the husband of but one wife, temperate, self-controlled, respectable, hospitable, able to teach, not given to drunkenness, not violent but gentle, not quarrelsome, not a lover of money.
AT THE SAME TIME, going to a seminary benefits more by helping a person serving God better. The only Apostle that didn't follow Jesus was Paul however, Paul did have extensive education background regarding Jewish Laws that were very useful for God to use Paul when He wrote the letters of the New Testament. Through Paul's letters, we have learned GREAT doctrines who was very educated and at the same time very spiritual.
I do have some concerns with some who are "professed preachers" in this world. Those who claim to follow and teach the "Word" MAY NOT be following the Word. This is where we are to understand what the Bible says about discerning and how teachers should behave and teach. I have the most respected preachers who tells their listeners how Christians are to test the spirits including their own teachings.
When I retire, one of my goals is to attend a seminary if God is willing.