First, I disagree that Jesus was all about peace love and harmony. I agree that is the image most choose to accept and that compared to the old God he is super. I am also happy we choose a loving God over a spiteful vindictive and jealous god. But the New Testament is rather explicit about what happens when Jesus returns to earth, and it fails to live up to the peace and love attributed (something like 99.99% of people cast into hell by the most ardent estimates, still something like 80% by most estimates). There are plenty of references that seem out of place for a person devoted to Love:
But why take my arguments on the topic?
(citations to King James,
http://www.biblegateway.com)
Jesus Said
Think not that I am come to destroy the law, or the prophets: I am not come to destroy, but to fulfil.
Matthew 5:17. It goes on to say that you shouldn't break even one of the least commandments.
Jesus Said
And as it was in the days of Noah, so shall it be also in the days of the Son of man.
Luke 17:26. Describing how God kicked Lots butt and will continue to kick butt in the time of the Son of Man.
Jesus said
But those mine enemies, which would not that I should reign over them, bring hither, and slay them before me.
Luke 19:27. Presumably he wants to have them killed out of compassion, mercy and love.
Seeing it is a righteous thing with God to recompense tribulation to them that trouble you;
And to you who are troubled rest with us, when the Lord Jesus shall be revealed from heaven with his mighty angels,In flaming fire taking vengeance on them that know not God, and that obey not the gospel of our Lord Jesus Christ:Who shall be punished with everlasting destruction . . . .
2 Thessalonians: 6-9. Flaming fire vengeance from our new loving God on anyone that worships differently. Isn't jealousy a sin and vengeance so Old Testament?
Hebrews has tons of things on casting people to perdition and how we should fear our living God. Revelations is nothing but loving God destroying things. But how are we to know? Even the Bible frequently talks about God sending delusions, false prophets, and messages in parables so distorted that people won't be able to properly understand them (and will therefor be damned). Personally, if a teacher intentionally made things confusing and flunked me, I'd be pissed.
In any event. It is clear that Jesus unconditionally loves people who believe he is the Son of a God, a quasi God himself and do what he tells them to. Well, he loves the other people too but hopes they are brought before him and killed and eventually he will return to Earth and cast them into a pit of eternal fire to suffer a most unimaginable fate for all time. Which really screws with my definition of unconditional and how you treat people you love. Frankly, loving people and treating them well when they do what you tell them to isn't that amazing to me.
But if we want to revert to the argument that the new God is a loving God:
So God changed his mind on some of the rules over the course of a couple thousand year. Now we are a couple thousand year removed from Jesus. Have those rules subsequently changed? And doesn't it seem strange that a perfect deity would need to revise his teachings (or is it because the perfect being created imperfect man in his image?) in what to him would be the blink of an eye? And if the New God is different than the Old God, why keep the Old Testament around when much of it is admittedly chronically horrible acts by/in the name of God?
You are reading into the context of a bronze age text that has been revised, redacted, and translated hundreds of times by men - often with open political motives. Certainly a difficult task for scholars and open to multiple interpretations. And given the number of interpretations it is highly likely that it is often incorrect. Which seems a dangerous thing to live by.
I understanding the theory. Old God was wrathful and liked to spite entire villages and his most ardent followers on a whim (or to prove how cool he was to an underling/Satan). New God is happy-go lucky and isn't cool with the things the old God told people to do. But Jesus never revoked or even spoke out against the vast majority of the laws (including slavery, as The South pointed our ad nasuem). Hence, some of the old rules still apply (10 Commandments) but others do not (mixing cloth, stoning people) - and each sect gets to decide which apply and how to interpret them.
But that kind of goes to the heart of the argument, we are choosing portions of laws handed down by a God that are still adhered to by a certain religious faith. To the Jews God never did away with their laws. To some fundamentalist Christians many of the old laws still apply. Even the version of the 10 Commandments isn't agreed upon by Protestants, Catholics, Jews or Muslims.
And none of that goes to the fact that most of the Biblical Laws are not laws in our secular society. Most notable the key one (belief in that particular God). Given all that confusion and the underlying problems, a monument to the 10 Commandments as a basis for anything seems inappropriate