Legalism, properly understood, is not about Christians obeying too precisely. It is also not about individuals having convictions that are their own private resolves. It is about seeking to be justified by means of the law. When Jewish infiltrators came to the early believers and said that they must be circumcised and obey the Jewish feasts in order to be true Christians (Acts 15:1), then they demonstrated New Testament legalism. We do have Christians with a spirit akin to the legalist, but their sin is that of being unloving or distorting responsibility or placing private convictions on others, not true legalism. In most cases, they are not seeking to be justified by the law (Gal. 5:4).
Jim Elliff