How can I prove from scripture that the 10 commandments are included in the Law of Moses? I've come across some people who teach that verses like Acts 13:39, Rom. 3:28 and Gal. 2:16 EXCLUDE the 10 commandments and the word "LAW" is only a reference to animal sacrifices and such. They then declare that we are justified by the keeping the 10 commandments. Daniel
So, you want to know how to prove that the very fundamental premise of someone's belief structure is false? These folks CANNOT allow their proof-texts of justification to be used against the fragile system they have built. Though they may be scripturally confounded by the numerous problematic texts they encounter along the way they will find a way to work it into their overall structure. Now, when one's system comes crashing down and so exposes the obvious he will require no proof.
Is this a common teaching in certain cults?
Actually, this is a very common argument among those who tenaciously cling to the moral law of God for justification. It's just that you don't often hear it so clearly stated until you get past their defenses and challenge their basic premises. The Law of Moses is easily categorized into three main aspects: civil (technical societal laws), ceremonial (sacrificial and worship system), and moral (beginning with the "10 commandments").
It is the legal mindset that segregates these integrated aspects of the law in order to preserve a system of fleshly justification. It is, after all, much easier to let go of the aspects dealing with both the Jews' ancient civil technicalities, as well as their worship and sacrificial system. But isn't it interesting to note how in hanging onto the outwardly applied moral code of Israel our own societies have re-established highly integrated civil and ceremonial aspects along side the moral, so that it has become "immoral" to break even "civil" or "ceremonial" aspects of the newly established legal unit?
Free truly means free, does it not?!