Why should believers not labor under the old system of Law?
Believers are delivered from the Law through the cross and joined to Christ, raised from the dead, to bring forth fruit unto God. The old system of Law is crucified and dead as far as God is concerned; it only condemned and produced fruit unto death, so they serve in newness of spirit, not oldness of the letter.
Les explains that when we were in the flesh, in the old Adam and spiritually dead, the motions of sins which were by the Law worked in our members to bring forth fruit unto death. Every time the Jew turned around, the Law condemned him; human nature is law-breaking, so the Law constantly put him down as guilty. But now, as a result of the Gospel, believers are delivered from the Law, that being dead wherein we were held, so we should serve in newness of spirit and not in the oldness of the letter. The old system of Law is now crucified, dead, and gone as far as God is concerned. Les also mentions Israel's veil, which was never taken away, because they could not understand that the Law was now finished and done, and that is why they still try to keep it today.
But now we are delivered from the law, that being dead wherein we were held; that we should serve in newness of spirit, and not in the oldness of the letter.