In effect, the medieval church said: God has done his part. Jesus qualified himself to be the Savior. He died to facilitate your salvation/justification/sanctification. In baptism we were said to receive initial justification. We were given a clean slate. From confirmation on it was up to us to do our part, to cooperate sufficiently with grace in order to present ourselves to God.
64. But does not this doctrine make men careless and profane?
No, for it is impossible that those who are implanted into Christ by true faith, should not bring forth fruits of thankfulness (Heidelberg Catechism 64)
Moralism and rationalism are twins. In Christian theology, where you see the one the other is nearby. In this context moralism refers to the doctrine that we are accepted with God (justification) and/or delivered from the wrath to come (salvation) through inherent, personal, intrinsic sanctification (holiness) and righteousness. Rationalism, in this sense, is the notion that in order for something to be true it must be comprehensively understood. In order for a rationalist to believe something it must make complete sense to him. Mystery must be removed. It does not take long to see how rationalism and moralism are related. How should a rationalist go about setting up a scheme to get people (Christians) to be good? He should set up a system whereby either their justification or their salvation is contingent upon their sanctification. This is, after all, how one gets results in the world, in ordinary experience.
Usually, if a boss wants greater efficiency and productivity from her employees, she sets up a system of incentives for her employees. If the boss is of the ordinary, uncreative sort, those incentives are likely to be negative. Fail to meet this goal and x (e.g., loss of pay, demotion etc) shall happen. A more creative boss might set up a series of positive incentives: meet this target and you shall receive y reward (e.g., extra paid vacation, flexible scheduling, company car etc). Whatever the nature of the incentive, the very structure is a covenant of works.
Life beyond the covenant of works is a covenant of works. I started working when I was 10. I delivered newspapers but I quit that in favor of basketball. When I was 14 I took a job a couple of days a week washing dishes in a local restaurant after school until 11:00 PM or midnight. One Saturday morning, after a late shift I overslept. When I woke up I called the restaurant to see if I still had a job. Nope. When I was 16 I took a job making deliveries for a local florist. My first day on my own I didn’t return until 7:00 PM and I didn’t get all the flowers delivered. Another pink slip.
A job is a covenant of works. That’s why they call it going to work and not going to grace. It’s about performance, about meeting the terms of the covenant. The terms of every job are: “do this and live.” School is a covenant of works. Term papers must meet certain standards. Mid-terms and exams must be sufficiently correct in order to pass. Civil life is a covenant of works. Break the speed limit and you risk being pulled over and ticketed. Run a red light, cause an accident, and you’re responsible. Break a law, pay the fine. Break enough laws and you will do time. This is why the Apostle Paul says that the magistrate does not bear the sword in vain (Rom 13:4). The sword is not a symbol of grace but of works righteousness.