I saw this article on a website which seems to have gone now but I found very helpful and I hope you do too
1. In discussing the two covenants, we are not refering to the division of the Bible into two sections, but to the periods of the two covenants on ground.
2. The Old covenant is the same as the Law, and the New is the Spirit (2 Corinthians 3:1-18)
3. The Old Covenant was targeted at only one nation – Israel. No-one outside of Israel was/is bound by the Law (Ephesians 2:11-12)
4. The New is NOT a continuation or extension of the Old. It is a replacement. (Hebrews 8: 7-13). Why? The Old was never intended as a permanent solution (Galatians 3:19-25)
5. Under the Old God spoke to people by prophets; but under the New He has spoken by His Son (Hebrews 1: 1-2)
6. The person who accepts one aspect of the Law is under obligation to keep the whole Law. Not doing so is condemnation (Galatians 5:3)
7. Submission to any aspect of the Law removes a believer from under grace and back into death (Galatians 5:1-4). Submitting to the Letter (the Law) kills a person spiritually (2 Corinthians 3:6), while doing away with the Law and living under grace (the Spirit) gives life.
Looking at this subject in details revealed major flaws in the teachings and practices of a majority of professing believers, including but not limited to:
b. Observance of firstruits and the other myriads of offerings
c. Submission to guidance and revelation from prophets
d. Seeking and depending on extra-Biblical revelations
The most shocking thing about this is the huge number of professing believers who are clearly not under grace by their many practices and beliefs – yet their leaders keep giving them a false assurance of salvation. It is both sad and shocking.