and to wait for his Son from heaven, whom he raised from the dead-- Jesus, who delivers us from the wrath to come.
The reason that scholars often mistakenly believe that Christ taught his "speedy return" is that they misconstrue passages like  Mark 8:38 and  Mark 9:1 as references to the Second Advent, whereas the reference, like some similar passages, refers not to the Second Advent but to the establishment of the kingdom of Christ, an event which did occur immediately.