"Backsliding." If you've been enjoying the message related to the gospel of grace for a while, you may not have heard the word for a long time. On the other hand, it is probably a regular part of one's vocabulary if surrounded by a legalistic landscape. "Backsliding" will have various implications that are defined very broadly amongst the denominational spectrum. How does a person come to be defined as a "backslidden Christian"? Does it mean a backslider is in God's doghouse? Is divine punishment hanging over their heads waiting to fall? Could it possibly mean one is in danger of losing their salvation that was found through belief in Christ—apart from works?
Let's look at this from a New Covenant perspective and scratch off one more worry from the legalistic list.
There are no chapters in the Bible specifically dedicated to the word legalism ... but the concept can be found throughout the pages. In a nutshell, it's the human effort to acquire God's acceptance and approval while being rewarded with eternal life and other blessings. There can be varying degrees of legalism, sometimes mixed with at least trace elements of the gospel of grace. But a little bit of leaven (religious law) will affect the entire lump of dough. Whether it's subtle or overwhelming, grace and law were never meant to be mixed.
How does one escape such a monster of a phony gospel message when it seems to be everywhere in a mixed-covenant culture? What is the cure for such a contagious epidemic? Just reading the Bible won't get it done. It will need to go beyond "solid grace teaching" and contextual understanding from the Bible ... which changes with the weather. It is by revelation from the Spirit of God, who assists in helping to grow in our understanding of grace and the Savior who will not allow us to take any of the credit for what He has done.