What is "Legalism"

The term "legalism" has a million applications :-).

But consider Paul's allegory:

Galatians 4:21 - 5:1   21 ¶ Tell me, you who desire to be under the law, do you not hear the law?  22 For it is written that Abraham had two sons: the one by a bondwoman, the other by a freewoman.  23 But he who was of the bondwoman was born according to the flesh, and he of the freewoman through promise,  24 which things are symbolic. For these are the two covenants: the one from Mount Sinai which gives birth to bondage, which is Hagar --  25 for this Hagar is Mount Sinai in Arabia, and corresponds to Jerusalem which now is, and is in bondage with her children --  26 but the Jerusalem above is free, which is the mother of us all.  27 For it is written: "Rejoice, O barren, You who do not bear! Break forth and shout, You who are not in labor! For the desolate has many more children Than she who has a husband."  28 Now we, brethren, as Isaac was, are children of promise.  29 But, as he who was born according to the flesh then persecuted him who was born according to the Spirit, even so it is now.  30 Nevertheless what does the Scripture say? "Cast out the bondwoman and her son, for the son of the bondwoman shall not be heir with the son of the freewoman."  31 So then, brethren, we are not children of the bondwoman but of the free.  5:1 Stand fast therefore in the liberty by which Christ has made us free, and do not be entangled again with a yoke of bondage.

The idea is that the natural offspring -- those not "promised" -- are related to God via Mt. Sinai, whereas the spiritual offspring -- those "promised" -- are related to God via the Jerusalem which is above.  It is probably the case that one could say "Mt. Zion," by arguing from other passages (Heb 12, Rev 14).

Therefore, to be "legal" is to be related to God as a natural (unregenerate) person, as typified by Mt. Sinai.  To be "gracious," or "spiritual" is to be related to God via the Jerusalem above, or Mt. Zion.

To be related to God via the Jerusalem above has no correlation with being exempt from the requirement for Christian behavior.  It is not "anti-nomian."

The real issue concerning Christian behavior is whether converted Christian behavior is brought about by a relationship to God's good law, which is in the mode of the First Creation, now fallen, (and which is typified by Mt. Sinai), or whether converted Christian behavior is brought about by a relationship to God by the Spirit in the New Creation, typified by Mt. Zion and the Jerusalem which is above.

Paul spends considerable time explicating this difference, when he compares the legal "do this and live," with the spiritual "believe in the Lord Jesus Christ."

The alternatives of legalism and spirituality have to do with the nature of the spiritual power-relationships which are active in a person's life.  A power-relationship to "do this and live," is a power-relationship to sin:

1 Corinthians 15:56   56 The sting of death is sin, and the strength of sin is the law. 

A power-relationship to the Holy Spirit through the Gospel of Christ is a power-relationship that delivers from the bondage of sin and writes the Law on the heart!

We hear a lot said about the need for Christian character.  It's true we need this, and the Scriptures will instruct us.  But, perhaps we need to pay more attention to the need for Christian faith!  Faith -- in the Gospel of Christ -- is associated with that power-relationship that delivers from sin and ultimately produces Christian character.  Sin began in Eden as a loss of faith.

Legalism has nothing to do simply with wrong methods of using sets of rules, or with making rules too "harsh."  Legalism is the advocacy of a power-relationship to the "do this and live."

Spirituality is a power-relationship to Christ which is only received -- by believing the gospel.  Faith is not a work.