 But I think it is certain that most of the early Christians understood these words of our Lord's ascension and coming again in glory.  They believed that He was coming again in a very little while during their own life-time, in a few months or years, to make an end of the world and to judge the quick and the dead.  And as they waited for His coming, one generation after another, and yet He did not come, a sadness fell upon them.  Christ seemed to have left the world.  The little while that He had promised to be away seemed to have become a very long while.  Hundreds of years passed, and yet Christ did not come in glory.  And, as I said, a sadness fell on all the Church.  Surely, they said, this is the time of which Christ said we were to weep and lament till we saw Him again--this is the time of which He said that the bridegroom should be taken from us, and we should fast in those days.  And they did fast, and weep, and lament; and their religion became a very sad and melancholy one--most sad in those who were most holy, and loved their Lord best, and longed most for His coming in glory. 
How long did Christians believe it would take for Christ's return?
A few months or a few years