To what were the Israelites not submitting, not subjecting themselves?...

To the righteousness that God has provided for every person.

It is to the conflict between the works of the Law of Moses, as kept by the Israelites, and God’s righteousness in Christ, that Paul is referring when he speaks of redemption by Divine grace rather than by works.

Unfortunately, Paul’s "redemption by grace" has been understood by many in our own day (as we emphasized previously) to mean the Christian salvation has little to do with the way people behave. This is a wresting of Paul’s doctrine and it leads to the destruction of the believer rather than to eternal life (II Peter 3:16).