What about how God had commanded circumcision, outlawed certain foods, commanded the death penalty for working on the Sabbath, death for homosexual sex, permitted or commanded slavery (Deuteronomy 20:11), permitted polygamy (many main Jewish men in the Old Testament had multiple wives)...
It seems that God has changed....
The Old Testament laws were for a few reasons.
I believe every law or command that God gave or gives now is for:
His overall long term plan or an important spiritual reason.
The ultimate good of the society.
or for our own individual physical, spiritual or mental well being.
Just because we don't understand a law or command doesn't mean there isn't or wasn't a good reason for it. We don't have all the answers and can't expect to know all of them while we are bound here in the flesh. Even Paul said we understand dimly.
1 Corinthians 13:12
For now we see only a reflection as in a mirror; then we shall see face to face. Now I know in part; then I shall know fully, even as I am fully known.
Man tends to be focused on the here and now, his immediate gratification and what feels good to him at the moment while God is focused on eternity. Obviously not 100% of the time but in general terms.
Circumcision
As handed down to Abraham, not as its done today-which is actually a man made perversion. Circumcision as given by God hasn't been practiced since 300 BCE. The foreskin was pulled forwards and only the very end cut. Not pleasant obviously, it was done as a blood sacrifice and to mark God's people as being different. It wasn't however most of the foreskin as has been practiced in the US. For one they didn't have the clamp which is required to stop bleeding out and two because the purpose wasn't to remove it. But when circumcision is mentioned today most people think of what is done in the US, which is completely due to John Harvey Kellogg and Victorian ideas of cleanliness. It was promoted as a way to stop masturbation because they believed it caused madness and epilepsy.
Certain foods
Some had symbolic spiritual significance and some was for health reasons. Under cooked pork for example can have Trichinosis.
Commanded the death penalty
Last I looked the US still has a death penalty, which means your country/society is okay with death as a penalty. So it can't be death that you are against but rather why they were given the death penalty. If mankind in your society can deem things worthy of death why be surprised if God does too? You simply disagree with God's decree of
what was worthy of the death penalty. The nations surrounding the ancient Israelite's thought nothing of burning babies in fires as a sacrifice. Man made laws have been much harsher than God made laws with no reason to many of them except laws based on what felt good to them or fear of evil spirits. They sacrificed babies to appease demons. God commanded the Israelite's not to take up any of the despicable practices that surrounding people were doing.
Deuteronomy 18
9 “When you come into the land which the Lord your God is giving you, you shall not learn to follow the abominations of those nations. 10 There shall not be found among you anyone who makes his son or his daughter pass through the fire, or one who practices witchcraft, or a soothsayer, or one who interprets omens, or a sorcerer, 11 or one who conjures spells, or a medium, or a spiritist, or one who calls up the dead. 12 For all who do these things are an abomination to the Lord, and because of these abominations the Lord your God drives them out from before you.
He gave those laws because he knew without them they would do the same. These were not cultured people.
Slavery
Biblical slavery is not the same as man made slavery. It was part of warfare. The warfare was based on nations committing evil practices not on skin colour. They were probably all brown skinned and basically of the same general race.
Then later a Hebrew could sell themselves into slavery to pay of debt rather than go to prison.
Now that isn't to say some people didn't try and make the Bible say what they wanted it to say to justify slavery, but that is a different thing. Many times the curse of Ham is quoted, but if you read the actual passage you can see it is a long stretch from what it says about ham-who is just one man- to the transatlantic slave trade. Not to mention that every race has at one time or another been enslaved. Slavery is not unique to black people.
Permitted polygamy
God did not want or approve of polygamy.
Just because the Bible records an event that occurred does not mean that God approves of the event. People do whatever they like whether it is agreement with God's word or not. It is God who instituted marriage and it was to be to one woman for life. That was marriage as was handed down by God to Adam, anything else outside of that was added onto by people.
Most times events were recorded for history, to show that not even the great people of the Bible were sinless-only Jesus was sinless and also to show why it was a bad idea. There were consequences recorded that followed many of the sins committed, not just polygamy. Some are not obvious on casual reading because sometimes the consequences occurred years later or were many smaller consequences such as affecting family happiness and unity.
For example Isaac was promised Rebecca as his wife after 7 years of work, but was tricked into marrying her older sister Leah instead. From there if you keep reading the action of Laban (father of the girls) caused a whole lot of family strife. God isn't encouraging anyone to go and copy them.
God's views have not changed but there was an Old Covenant and a New Covenant and there are changes between them. For one thing God says he put laws (general moral principles) onto the hearts of mankind.
Hebrews 10:16
"This is the covenant I will make with them after that time, says the Lord. I will put my laws in their hearts, and I will write them on their minds."
It wasn't always this way.
How the ancients thought is not how we think. Taking what we know and think and trying to place it on the ancients doesn't work, in some way they were fundamentally different. They followed God's laws (and failed at them) because this was what they were told to do by God. Many only followed due to fear, they didn't feel them as moral principles the way we do. Those who actually followed God out of love were special, and get mentioned in the Bible for their faith as being unique.