Some people get confused about how the OT law pertains to us as Christians today. Someone asked me about the fact that homosexual practice is banned in the OT law and we take that seriously, but we don’t adhere to rules about slavery, planting crops, etc. Here was my answer (sorry it is long).
The Old Testament law (Exodus, Leviticus, Deuteronomy) was the constitution for the Israelite people back in biblical times. It contained overall moral prohibitions (as our laws do today against things like murder), as well as practical ways to deal with real-world situations from day-to-day (modern example: back in the 1970’s when there was an oil crisis, the speed limit was adjusted to 55mph because that is the optimum speed for fuel efficiency. The speed limit is different now on different types of roads. There is nothing special about 55 or 65 or 70mph. Now, we are more concerned with crash fatalities than fuel economy. This is a practical law in place for peoples’ well being, not a moral law.) God gave the Israelites practical laws for their day. In their day, slavery was a cultural reality, so God gave laws to govern it (that does not mean He created slavery or condoned it – He gave laws restricting what must be done for a man who has multiple wives, same thing). There were laws about crop production, mold, fabric in garments… practically everything was spelled out for His people. Well, since the OT law was the constitution for a specific nation thousands of years ago, and because Christians do not live under the authority of the ancient king of Israel, but under the rule of Jesus Christ, that constitution no longer applies to us. Christians who say it does are misguided. However, there are moral aspects of the OT law that were in place before the law was given (see Genesis 2 about God’s ordination of marriage) as well as after the law in the New Testament (Jesus taught that marriage was between a man and a woman and Paul and others wrote against homosexual practice in places like Romans 1). So, the simple answer is this – we DO take the OT law literally, but it simply does not apply to us today because we live under King Jesus and are not part of the ancient kingdom of Israel to which the OT law applied. That’s why Christians don’t get excited when people plant different crops side-by-side. I assure you, if that prohibition was in the NT, we’d be motivated to speak up about it. There are moral aspects of the OT law that Jesus gave to Christians today. Marriage is one of those things that is woven throughout the Bible from Genesis to Revelation. I hope this makes sense.
Something to put in your memory when this type of question comes up.