All the Apostles except John died as Martyrs. John died a natural death in AD 96. The word "martyr" comes from the Greek word, 'martyres' which means one who bears witness. The Apostles as well as many believers bore witness to Jesus Christ, through persecutions and martyrdom. The first three centuries of the Christian era were ages of persecution and martyrdom for the Christian Church. The more it was persecuted the more it flourished The steadfastness and integrity of a martyr moved several others to conversion and confirmation in faith. In AD 313 when the Roman Emperor Constantine issued an edict, the persecution was stopped and Christianity was accepted as a state religion.
In the beginning of the Christian Church all the opposition it met with was from the Jews. Judaism was a lawful religion in the Roman Empire and the Romans did not distinguish the Christians from the Jews (Read Acts. 18:12-17,25:6-12). At times they interfered either to protect the Christians from the Jews or to persecute them being instigated by the Jews. With the spread of the Church among the Gentiles and with the enmity of the Jews, the identity of the Church as a new group, distinct from Judaism, became more and more manifest The Roman authorities began to treat Christianity as an unlawful religion.
During the Apostolic period (AD 60-96) the Church faced two major persecutions at the hands of the Roman Emperors, Nero (AD 54-68) and Domitian (AD 81-96). In AD 64 a great fire devastated Rome. It was said that the Emperor Nero himself had set the city on fire. He tried to escape the accusation by putting the blame on Christians. Nero persecuted and killed many believers. It was in this persecution that St. Paul was murdered by sword and St. Peter was crucified.
Emperor Domitian who ruled Roman Empire from AD 81 to 96 considered himself divine. He demanded that people should worship him. Those who refused were persecuted and killed Many Christians received martyrdom at the hands of Domitian. It was during the end of his reign that Domitian exiled St. John to Patmos. From there John wrote the Book of Revelation to strengthen the seven Churches of Asia.
The Church after the death of the Apostles continued to be persecuted by the Roman rulers. At the same time it had to face a more serious danger, heresies. The major heresies of the period were Docetism and Gnosticism. Even at the time of the Apostles these heresies were operative.
The Fathers always safe-guarded the faith of the Church. They refuted the false teachings and kept the purity of the Gospel of Christ. There were four distinguished Fathers during the period AD 96-200 They were Clement of Rome, Ignatius of Antioch, Polycarp of Smyrna and Irenaeus of Lyons. The first three Fathers were called the Apostolic Fathers. They were the contemporaries and the disciples of the Apostles. Polycarp, the last of the Apostolic Fathers, died in AD 155. After the Apostolic Fathers, Irenaeus of Lyons, who flourished during the latter half of the second century, was a distinguished Father of the period. Of these four Fathers, Ignatius wrote much against Docetism and Irenaeus against Gnosticism.