Why did Christianity spread throughout the Rome world. We have to use the race format for this question.

Well, missionaries (a person that promotes Christianity in a foreign country) and apostles were spreading Christianity through Rome. Eventually the emperor became Christian and churches were quickly build in the Rome Empire. And also Rome was very poor at that time and the emperor that allowed Christianity was Constantine.

I hope this helps I wrote it personally.

  the domino theory states that  if one country in a region came under the influence of communism, then the surrounding countries would follow in a  domino  effect.