OK, I suppose there is use of a nonstandard definition of
legalism which is properly given in the Oxford Dictionary:
1.1 Theology Adherence to moral law rather than to personal religious faith.
Yup. The Oxford Dictionary is too simplistic.
And rejecting the idea Christians should adhere to moral law is antinomianism, which is a heresy in Lutheranism, Methodism and some Reformed traditions.
This is how legalism should be understood.
“Legalism exists when people attempt to secure righteousness in God’s sight by good works. Legalists believe that they can earn or merit God’s approval by performing the requirements of the law”
Legalism believes that their good works and obedience to God affects their salvation. Legalism focuses on God’s laws more than relationship with God. It keeps external laws without a truly submitted heart. And legalism adds human rules to divine laws and treats them as divine.
www.christianity.com