Priesthood of the Believer

Do people have approach to God only through a clergy class, priests, church, an organization, a certain denomination, or is approach to God directly through Jesus Christ, and him alone? What is the priesthood of the believer?
The Bible is written so that anyone can read and understand it for themselves, but each person has a serious responsibility to use the Bible correctly, “accurately handling the word of truth” (2 Timothy 2:15 NASB).
“We do not write you anything you cannot read or understand”—2 Corinthians 1:13 NIV