As for Joe Carter, honestly my opinion of him is growing more and more mixed. I can't remember when the last time "Evangelical" Outpost even mentioned God or Jesus.Now for the record, I spend a lot of time talking about guns, my girl, and politics. But my real beef is not that christian bloggers need to talk about Jesus to establish their Evangelical equivalent of street cred. That isn't it.
My beef is that Evangelicals tend to throw around words like "christian" and "biblical" a lot. However those words have meanings, "of Christ" and "of the Bible." If you say something is christian/unchristian, you probably should be able to cite an example where Jesus or at least an apostle spoke for or against it. Similarly if you say something violates biblical principles or a biblical worldview, cite a frickin' verse. If you can't cite a verse, paraphrase an example. If you can't do that, then resort to quoting John Piper or C.S. Lewis. But realise that you are quoting secondard sources at that point, not primary ones.
This isn't hard and the apostles themselves did it all the time. Check the various speeches in the New Testament for examples. Peter's speech in Acts 2 is a good choice. The Gospels make reference to prophetic books all the time too.
In the end though, just be careful about using words like "biblical". It becomes a bludgeon after a while and if you don't validate your "biblical principles" enough they can become deeply colored with your own prejudices. Without the citation you are just committing an appeal to authority and that doesn't impress me much, nor should it.