Any topic (writer’s choice)

This is an essay for a class on the history of ancient Rome. Please write three to five paragraphs in basic English to answer the following three questions in detail: How and why did Christianity move from being a persecuted cult to the state religion of the Roman Empire? What was unique about Christianity that caused Roman authorities to persecute it (Roman tradition was tolerant about religion), and what was unique about Christianity that enabled it to survive and ultimately prevail?