The Greek word episkopos occurs five times in the New Testament (Acts 20:28; Philippians 1:1; 1 Timothy 3:2; Titus 1:7; 1 Peter 2:25). The word is translated “bishop” in the King James Version, but “overseer” in most modern versions. The word means an overseer or superintendent. The term is used in reference to Jesus Christ in 1 Peter 2:25 where he is described as the Shepherd and Overseer of our souls. The early Christian churches seemed to have several “bishops” in each major town. They are also called elders. The bishops/elders took on leadership in the early church.
The qualities that are required for a bishop are listed in 1 Timothy 3:1-7. He must be of blameless moral character, a good teacher, not a drunkard or lover of money, and must be able to manage his own family.
There is no evidence that the word was used as a title in the first century churches.