Why should Christians avoid legalistic preaching?

The writer warns against diverse and strange doctrines, indicating that any teaching which promotes salvation through human efforts leads away from the true gospel of grace. Such preaching can give false assurance and create a burden of trying to attain holiness through personal works instead of resting in Christ's perfect righteousness (Colossians 2:8). Legalistic preaching is detrimental to the soul because it fails to offer the freedom and assurance found in the truth of the gospel, which affirms that Christ has completed all that is necessary for our salvation.