Hi Ken, I am glad you asked. You are very perceptive. Are Christians under the old covenant. Didn't Jesus ratify the new covenant with His own blood at Calvary?
The old covenant was for one nation, Israel. No other nation or people were under the laws of that covenant. Biblical Israel ended at the Cross, but the Jews were not scattered all over the World until 70 years later when the Temple was destroyed. The Levitical system came to an end. The covenant no longer ruled the Jews. The 10 commandments were part of that covenant. Ex 19:5-6 In fact scripture tells us it was the covenant.
Paul, in the second letter to the Corinthians, stated the following:
7 Now if the ministry that brought death, which was engraved in letters on stone, came with glory, so that the Israelites could not look steadily at the face of Moses because of its glory, transitory though it was, 8 will not the ministry of the Spirit be even more glorious? 9 If the ministry that brought condemnation was glorious, how much more glorious is the ministry that brings righteousness! 10 For what was glorious has no glory now in comparison with the surpassing glory. 11 And if what was transitory came with glory, how much greater is the glory of that which lasts! 2Cor3:7-11
Those verses along with many more sure do prove to me that the 10 commandments are no longer in force. They were the guide for Israel and the Holy Spirit is the guide for us Christians. Transitory means temporary and the verses are written in the past tense. When addressing the 10 commandments I use the term "defunct" because most people believe we are subject to them. All they could do is point out some sins and tell the Israelites to keep the Sabbath every week. Everyone should know the real truth.