We have so emphasized the idea of never acting in our own self-interest, that we ignore the continuous appeals of Scripture to be motivated by the fact that following our Lord is not only right, but smart. And sin is not only wrong, but stupid.

Motivation to work is a test of who people are serving. If they view it as only serving earthly owners and authority figures, their motivation will be lost.

The problem with short-term rewards is not that it's wrong to receive them, but that it's wrong for them to be our primary motivation for doing the work. If we take Matthew 6 seriously, when we offer people their name on a brick for giving to a building offering we're saying "Hope you enjoy this brick, because if this is why you're giving, the brick's all the reward you're going to get."

I read this question and answer, from Paul Tripp on the Desiring God blog. For those of you not familiar with Paul, he's the president of Paul Tripp Ministries, whose purpose is "to place the truths of the Gospel—the person and work of Jesus Christ—in the middle of the messy and confusing situations and relationships in which every person lives."