There were many reasons given for the persecution of the early church which included social, political economic, and religious. There were varying degrees of persecution well into the third century which helped to shape the church. Some early Christians abandoned their faith all together. Others stood firm for a time but acquiesced once brought before the Roman authorities and offered the appropriate sacrifice to the gods allowing them to receive a certificate attesting to their compliance. Still others obtained fraudulent certificates and avoided offering a sacrifice to the Roman gods.
Since Emperor Decius’ goal was to create apostates rather than martyrs, there were relatively few Christians who died during his persecution. Those who did were referred to as “confessors” and were honored in the Christian community.
Decius’ persecution was brief and ended in A.D. 251 when he was succeeded by Gallus who set aside the policies of his predecessor. This left the Christian church with a problem: what to do with those who “lapsed” during the persecution? Was one who ran immediately to comply with Decius’ edict to offer a sacrifice to Roman gods the same as those who denied their faith but then returned to the church while the persecution was still in progress? What of those who purchased fake certificates? Who was to have the authority to forgive the lapsed and welcome them back into fellowship? Divisions over whether purity of forgiving love has had a tremendous impact on the church that can still be felt in our own day.
The various persecutions of the Christians had an impact on their theology and the practice of their faith. Apologists had to sharpen their thinking in an attempt to demonstrate to the Roman authorities that Christianity was not opposed to imperial policies.
Early Christians would sometimes gather in the catacombs though this was not for secret meetings but rather because it is the place where many heroes of the faith were buried. Christians believed that communion joined them together with more than themselves and Christ but also with their ancestors in the faith. Unity was very important in the early church and when it became impossible for all of the believers in a city to gather together, bread from the communion of each congregation would be sent to the bishop of the city to be used other communion ceremonies.
A final note: hierarchy of the church did not seem to be a response to the persecution of the church. It was in response to the heresies (i.e. Gnosticism) in the late second and early third centuries. Sadly there is still persecution of Christians taking place today in many places around the globe.