How did the Roman Empire's roads help spread Christianity?

Answer

In pre-Roman times, new religions could generally only be spread by conquest. It was simply too difficult for missionaries to go out into new territories to spread the words of their gods.

The Roman roads made travel both easy and safe. For example, Paul could travel by road throughout Syria, Asia Minor and Greece quickly and with safety. Messengers could take his epistles to distant communities and return with the responses of those communities in a relatively timely manner, so that Paul could maintain contact and respond to issues that impeded his message.