For many Christians it's fairly easy to walk into a corporate worship service, sing a few songs, listen to a sermon, and walk right out the door without any meaningful interaction with fellow believers. The people sitting beside us in the pews are our spiritual brothers and sisters, people for whom Christ died. We ought to be concerned about them. In fact, 1 John tells us that not loving our fellow believers is evidence that we have not passed from death to life. The way we treat fellow believers is indicative of our relationship to Christ.