Scott Lencke has a good post up on why he doesn’t believe we should believe the popular idea that the church was born at Pentecost (Acts 2). Scott lays out some very good reasons why we should see God’s people through the lens of continuity rather than trying to divide Israel and the Church up. You’d do well to check out Scott’s thoughts.
In the charismatic world, I think you find a lot of preaching that tends to force very sharp distinctions between the Old Testament’s Israel and the New Testament’s Church. It’s common to hear things about people in the OT being saved by their works and people in the NT being saved by faith (I’ve blogged before why I totally disagree with that). There’s also a lot of preaching that tends to connects Acts 2 to the birth of God’s people, the Church, while almost completely ignoring God’s previous work in Israel. It’s almost as if some of the preaching I have heard reduces the Holy Spirit as being absent until Acts 2. This makes for some good “Pentecostal” preaching because you can then emphasize that the things that happened in Acts 2 can happen today, so get ready for Spirit baptism (at least that’s how these types of sermons come across).