Paul wants to be alive when the Lord returns because he does not want to be “naked,” i.e., without his body. Paul expresses the dilemma in a different context in Phil. 1:21-26 where he writes that it is good to remain on this earth and to serve Christ, but it is better to die and to be in Christ’s presence, even if it means that one without his resurrection body for a time.
Remember that this idea that our bodies don’t matter didn’t come from the Bible but from Greek philosophy. The Bible teaches that we are intended to be the way God created us in the Garden: body and soul (or spirit, if you prefer), material part and immaterial part. Paul’s teaching here regarding the Resurrection is not that we discard our bodies, but that we are given new bodies (this is what Paul is talking about at the end of v. 4).
Sometimes people will say of their deceased loved one’s body, “That’s not him (or her),” but that’s not the Scriptural view. In the Bible, one’s body is always associated with the person because it is a part of the person. That physical part of the person is not animated between death and the Resurrection, but it is still part of that person and will be absorbed and changed by the Resurrection body.
Note: Though the body is inactive between death and the Resurrection, there is no Scriptural teaching that the soul is inactive and, indeed, the Scriptures teach the exact opposite. V. 8 says that once we are absent from our bodies we are in the presence of the Lord. This verse also contradicts the notion of purgatory, since it allows for no period of purging after death before seeing Christ.