Sin begins with the imagination. In order to work ourselves loose from the world as God made it, we have to imagine that it is a different kind of place than it is. John Bunyan once wisely said that the sinful soul “entertains the sin by its imagination.” He adds that “sin thus attacks at the level of the imagination first.” This is why how we feed the imagination is so important.
This is also why many Christians in strong believing communities have trouble doing business with God directly, particularly children growing up in such communities. They imagine that sin and guilt are down on the horizontal level only, and they assume that if they have patched it up with other people then they must be somehow right with God. But it actually flows in the other direction. If we walk in the light as He is in the light, we then have fellowship with one another (1 John 1:7). Water doesn’t flow uphill, and neither does forgiveness. Get it right with God first, in the name of Jesus, and then let it flow downhill to your neighbor.
Faith sees Christ in your neighbor, but there is a form of unbelief that substitutes your neighbor for Christ. But then, when Christ is absent, by taking the first place your neighbor actually finds himself ill-served. When you are not in fellowship with the source of all love, then how can you love? This error is to replace the Creator with the creature, which is quite a different thing than seeing the glory of the Creator through all His creatures—including your neighbor. Although this seems very easy to us, it actually depends on a convoluted act of the imagination.