Based on the timeline you've started, the missing event that coincides with the year 36 CE is:
Paul the apostle has a vision of Jesus.
The completed timeline would look like this:
- Spread of Christianity
- 4 CE - Birth of Jesus
- 30 CE - Jesus crucified
- 36 CE - Paul the apostle has vision of Jesus
- 64 CE - Great Fire of Rome occurs
- (Further events can be added from the original list)
- (Follow-up events in the timeline could include)
- Constantine's conversion to Christianity
- Edict of Milan issued
- Council of Nicaea meets