As evidenced in Scripture, there are signs that reveal that someone is truly an apostle. Apostolic doctrine is not the views and beliefs of someone who calls himself/herself an apostle by title but not in power and purpose.
It's entire purpose is to preach boldly the message of Jesus, His redemptive work on the Cross, His Resurrection, and His call to those who follow His teachings that is found in the 27 books of the New Testament. It gives an account of His truth, His power, and His Kingdom (earthly and Heavenly) according to and by His disciples who witnessed and could attest to its validity.
Many have misinterpreted the true signs of an apostle and what being an apostle who believes in apostolic doctrine truly means. Please read Acts 2:42-47 and also 2 Corinthians 12:11 for more clarity.