In order to define Apostolic you first must define what is an Apostle?  An Apostle by Greek definition was simply one that was sent, a messenger.  This title though refers to the 12 men that Jesus chose to carry his message after his death and ascension into heaven.  In the first four gospels (Matthew, Mark, Luke and John), you will find the training that these men went through, and what they were taught.  Then in the book of Acts you will find what the Apostles did with that training.  Every denomination will agree that the first church was started during the book of Acts.  Also this period of church history, beginning with the Day of Pentecost (about A.D. 30) and ending near the conclusion of the first century (about A.D.100) with the death of the Apostle John, was called the Apostolic Age.  During the Apostolic Age, all the books of the New Testament were written, including the four gospels, the Book of Acts, the letters of Paul, the general letters, and the Book of Revelation.  So being Apostolic simply means that we believe and follow what the Apostles did with the teachings of Jesus.

What were some subjects that Jesus taught?
• I and My Father are One
• Go evangelize the world
• Repentance and Baptism should be taught in His name
• Being born again by water and Spirit
• By faith you could be healed