and to wait for his Son from heaven, whom he raised from the dead-- Jesus, who delivers us from the wrath to come.
Paul did not expect the Second Advent in his lifetime, because he speaks of his own resurrection from the dead, along with the resurrection of all the Corinthians, as an event scheduled for the future  (2 Corinthians 4:14). Furthermore, his saying, "We shall not all sleep"  (1 Corinthians 15:51) refers to the ultimate fact of Christians who may be alive at the coming of the Lord, and not either to himself or the Corinthians of his generation.  It bears this construction as easily as it bears the one which makes it a certainty of the speedy return of Jesus.  Furthermore, in these very letters to the Thessalonians, written long before the Corinthian letters, Paul affirmed that "The coming shall not be except the apostasy come first"  (2 Thessalonians 2:3); and the apostasy was an event which Paul clearly understood as involving a great deal of time.