Dr. John Fonville, in the third part of his sermon series entitled Threats To Christian Freedom: Legalism, discusses two types of works righteousness about which Paul warns the Church in Galatia in the 5th Chapter of his Epistle to them, and gives examples of each that include theologies that, by this site's standards, are Christian denominations. He contrasts these types of theological legalism with functional legalism, which he describes as grace-centered Christians who unintentionally judge themselves according to the law.
The first, called simply legalism (nomism), includes Christian theologies and other religions that teach that salvation itself- justification in the final judgement- is not imputed but is earned by works during life. He cites Mormonism, Jahovah's Whitness, and Islam as examples of theological legalism, as well as Christian denominations that teach that a salvific work like baptism or other sacrament is required for salvation. Contrary to what it may seem, this type of legalism actually diminishes the law, since the standard of the law must be lowered in order to be achieved by the individual. Ultimately in this theology, the sacrifice and divinity of Christ are of no consequence, as he becomes simply an example of righteous works and not the source of righteousness.
The second, called covenant nomism, teaches that while the initiation of the salvific process is a result of grace and election, both sanctification and ultimate justification are a result of works. In other words, you get in by faith, but you stay in by works. This is what Paul means when he asks rhetorically, "Are you so foolish? After beginning by means of the Spirit, are you now trying to finish by means of the flesh?" Dr. Fonville includes charismatic revivalism with its alter calls for rededication, the Roman Catholic Church with its doctrine of penance, and first century Judaism as examples of this type of works based righteousness. In this theology, the effectiveness of God's grace, the existence of the Spirit in the life of the believer, and the believers unity with Christ are discarded.
A remedy to both of these types of works based righteousness in the Church, Dr. Fonville concludes, is the constant exposure to the sound Gospel of salvation by grace through faith, citing 2 Peter 1:12-13,
Therefore, I will always be ready to remind you of these things, even though you already know them, and have been established in the truth which is present with you. I consider it right, as long as I am in this earthly dwelling, to stir you up by way of reminder,