Legalism is keeping a set of rules to make one right with God.
Dogmas are the rules of man elevated to the authority of God's Word.
Pharisees were legalists of Jesus' day lording their dogmas over the people and thus nullifying God's Word.
Today you'll find these kind of people in the church who will say the following is of the devil or sin:
drinking alcohol (you can drink but don't get drunk. Jesus made 6 kegs of the best wine in the universe and drank wine. Do be considerate of those who are alcoholic.)
You can't eat certain foods like pork, meat, shell fish...
You can't eat, have fun or do anything entertaining on a certain day
listening to or singing secular music (rock, hip hop, whatever). Paul quoted from Greek Pagan poets in Acts 17:28. Which presupposes he was familiar with the poem.
going to the movies
dressing a particular way (skirts, t-shirts, shorts, slippers, bare foot...).
questioning the pastor's teaching
Then they'll tell you that you have to:
Saturday/ Sunday Sabbath keeping
attend meetings (cults love indoctrinating peeps by their constant meetings)
speak in tongues, slain in the spirit, holy laughter...
tithe (this is NOT for the NT Christians but was for Jews) or give offerings
wear a dress, suit, and cut your mustache or beard
Watch out for control freak pastor/ leaders.
There are so many legalistic ideas running around. One needs to be a Berean and test everything by God's Word (Acts 17:11). Watch out for these unbiblical dogmas and be ready to correct those with God's Word. Churches love to teach moralism (another form of legalism) in which you are saved by Grace but kept in the faith by your good works. Under this false doctrine one can lose their salvation if they rack up enough bad works. How stupid! The Grace of God saves one completely.
BEWARE OF CHURCHES, ORGANIZATIONS, PASTORS, TEACHERS WHO TEACH AND PUSH RULE KEEPING AS A MEANS TO BE SAVED AND KEPT IN RIGHT RELATIONSHIP WITH GOD.
The LORD is The One who Authors one's faith and keeps one in forever.