The Old Covenant was not technically legalism. The Jews had turned into a system of legalism. Abraham was justified by faith just like everyone else in the Old Covenant. The Jews changed that. Obeying God is not the problem, it is leaving out God's grace (See the Parable of the Tax Collector). It is leaving out love, faith, justice, and mercy (of which Jesus criticized the Pharisees for - see Matthew 23:23, and Luke 11:42). Even if the Jews were doing things correctly (which they were not), the Old Covenant had ended. The blood of goats and bulls never took away sin. Obedience was not the issue. Circumcision at one time under the OT was a part of the salvation process (See Genesis 17:14). But Abraham to FIRST BELIEVE and not be circumcised in order to be saved (Romans 4:9-12). But seeing we are under a New Covenant with New commands, things like circumcision do not even apply anymore. Yet, the Jews took the old law and they twisted. We are not even under the Old Law anymore contractually speaking and they still were not doing things correctly under the Old ways.
At the Jerusalem counsel, they addressed the heresy of trying to be saved by FIRST trying to be circumcised and or by trying to saved by obeying the WHOLE of the Law of Moses (When the 613 laws of Moses did not apply anymore contractually speaking):
- Acts of the Apostles 15:1 says, “And certain men which came down from Judaea taught the brethren, and said, Except ye be circumcised after the manner of Moses, ye cannot be saved.”
- Acts of the Apostles 15:5 says, But there rose up certain of the sect of the Pharisees which believed, saying, That it was needful to circumcise them, and to command them to keep the law of Moses.”
- Acts of the Apostles 15:24 says, “Forasmuch as we have heard, that certain which went out from us have troubled you with words, subverting your souls, saying, Ye must be circumcised, and keep the law: to whom we gave no such commandment:”