adapted from How People Change.Much of what we consider to be good becomes the means through which the Gospel is supplanted. If we are honest, we will see that in some way we are all guilty of consistently supplanting the Gospel. It becomes secondary and our own efforts and wisdom becomes primary - sheer idolatry.
Formalism:
Formalism seeks to be apart of everything that the church is doing. It is faithfulness to a church calendar. It is works oriented with aggresive physical involvment and passive spiritual engagement. This is done so that I retain control of my life, my time, and my agenda. It is often seen a healthy aspect of a good life, however, it often reduces the gospel to participation in the meetings and ministries of the church. God hates formalism. (Is. 1; Matt. 23:23-28)
Legalism:
Legalism seeks to establish rules and standards for which Scripture does not. Hence, God is a god of unreasonable rules and harsh judgment. There is little joy in the life of a legalist because there is no grace to be celebrated. It is all about the performance of gaining a position before God. Hence, the gospel is reduced to what I accomplish instead of what Christ has done. God's requirements for me as a sinner really aren't that difficult which means God really isn't that holy. However, in assuming my righteousness comes from conformity to my own established standards, I supplant the gospel with another gospel - my own. I become the standard of holiness and the saviour of my sin. God hates legalism. (Gal. 1:6-10)