I had to read The Weight of Glory by C.S. Lewis for my ethics class this semester and I wonder why I never read it before! Here’s my summary of the content.
Many people think unselfishness is the greatest virtue, which means self-denial in some way. To Christians throughout history, the greatest virtue was love. While self-denial is taught in the Scriptures, it is not an end in itself, but a means to follow Christ, which is a teaching in Scripture filled with appeals to self-interest. So our self-interest is important to God and should be important to us, the problem is that we have weak desires for small things rather than strong desires for the best things: God and eternal life with Him.
This does not make Christianity a “mercenary” affair. Doing an action for the sake of a reward is only immoral when the reward does not have a natural connection to the act. For example, marrying for money is self-interested in a bad way because the money is a tacked-on extra that is not a natural part of marriage. However, marrying for the blessing of being with the woman you love is a natural result of marriage and a perfectly legitimate reason to get married.
Sometimes there are rewards to be gained naturally by certain actions that we are not aware of yet. Enjoying Greek poetry is a natural reward for learning Greek, but a student of Greek might not know this blessing yet. He has to do it in order to pass his classes or to please his teachers, so in a sense he is being “mercenary.” But the student of Greek will begin to enjoy it more and more and he will likely already have an interest in English poetry, which foreshadows more blessings to come when he is able to read Greek poetry.
Christians are in a similar situation to the Greek student. We cannot be fully aware of the blessings we get so it feels like drudgery at first to be obedient to God, but over time we come to know the rewards to a small extent and come to learn that the blessings we receive now, though of diminished value when compared to Heaven, foreshadow the blessings we will have with God. This is why we cannot think of our worldly blessings as ends in themselves or begin putting our trust in them, because they are only shadows pointing to what is to come. All of us have a longing for paradise and fulfillment that points to Heaven in the way that our hunger points to food, but we must not let modern philosophies and distractions silence that longing. There will also be glory for us in Heaven, which means approval from God or fame with Him rather than fame and approval from others. This is a natural reward of love that we desire for following and loving God.