Legalism is the belief that the way to please God and secure access to heaven is by complying to a set of regulations. This does two things. First, legalism robs us of any peace and joy the Gospel offers to us. When we are governed by fear we flip faith on its head. We begin to put our trust in something that neither has the power, nor was it ever intended to keep us safe–namely, our own ability. The Gospel reminds us that we are unable and incapable of meeting every regulation that God has for holiness. When we try to live out the Gospel in this way, we kill ourselves a thousand times a day.
Second, legalism distorts the God the Bible describes, who extends grace to sinners. God becomes a tyrant rather than a father. God is capricious and not gracious. God becomes impatient, petulant, and vindictive when we fail to live up to the standards legalism imposes. None of these attribute describe God. And yet, this is how we feel when legalism is the guiding theological lens we see through.
Legalism over promises and never delivers. It fosters a combative mindset and a environment of one-upmanship that is unhealthy for the church and unbecoming of a follower of Jesus. Legalism is a poison withing the soul of a believer and there is only one cure. We have to have a sound and true understanding of what the Bible says. This is the only remedy. The best antidote to legalism is good theology.
This means that every Christian should become a better theologian. We already are theologians. The only difference between many of us is the time we spend getting our theology right.