Sorry but I’m going to jump right over the rest of this thread because I’ve got to respond to this post. The notion that Jesus “changed stuff” is central to Christianity, and even more so to the various protestant denominations. I know nothing of your religious beliefs of level of education so will presume a minimum/nothing and work from there.
Before I can say anything about this I need to go back a step into the old testatment. If you ever run out of things to do on a rainy afternoon and want something to read, have a flick through it. If you look at the first five books (specifically exodus and leviticus) you will find a lot phrases that start with “thou shalt”. Some of these were quite high level, like the ten commandments with “thou shalt worship but one God and no other” and “thou shalt not kill”. There were also a lot less well known ones, like the prohibition against mixing fabrics when making clothes.
When Jesus Christ (in Hebrew “he saves”) appeared on the scene the Jews were effectively suffering under the weight of their own religion. The sheer number of prescriptions and proscriptions had reached a point where it was impossible for the ordinary person to obey the word of God (whether they were trying to or not) in day to day life. This wasn’t helped by a theocratic upper class in the form of the pharisees, sadducees and scribes who were quite happy to tell people that they were breaking the law of God for carrying a needle more than two thirds of a mile on the Sabbath if they were a tailor (because that then constituted work, which you were forbidden to do on the Sabbath) but weren’t too concerned with the whole compassion for humanity bit. Jesus makes his displeasure to this deep rooted hypocrisy quite clear in Luke in his “whoa unto you pharisees” etc speech, telling them they keep the outside of the cup clean but the inside dirty i.e. they were happy to follow the visible, physical laws, and condemn others for not doing so, but they had lost sight of what those commandments and rules were there to do - namely obey God. The God of the final years of the BC period was more akin to a ruthless judge supported by an unthinking or feeling police and court who saw no problem in sending someone to prison for life for theft because they stole a loaf of bread they were too poor to buy to feed their starving children. (I’m using an extended metaphor here, by the way.)
In the system of law set out by the old testament, the Mosaic Covenant, man had to follow the laws of the Torah and the later “secondary legislation” that came out of the religious classes. If he failed, they had to make a sacrifice to God according to the law broken (there are some quite detailed breakdowns of what sin requires what sacrifice in the old testament as well). All of these sacrifices had to be made at the Temple of Solomon - God’s own fine collection agency, if you will. Oddly enough there were some very successful businesses that operated in and around the Temple at the time, selling sacrifices and changing money for instance (Jesus wasn’t too thrilled with them either, profiting as they were on the suffering of the people).
Jesus changed all this by declaring there would be a New Covenant - God recognised that people could no longer obey his word despite their best efforts, and that the fat cats of the time weren’t helping. Thus, in his infinite compassion for humanity, he incarnated himself as a human (his son) to be the ultimate sacrifice. Jesus was to be the lamb of God, akin to the actual lambs that were sacrified at the temple for serious crimes. He was to be perfect, born without sin (through immaculate conception, and therefore unsullied by original sin) and he would live a life of perfect virtue. Also, more importantly, he would know that even though he was sinless, he was to be sacrificed to atone for all the sins of man. Skipping ahead, in the Passion narratives, Christ is seen willingly giving himself over to the Roman authorities, denied by his followers, cast down and physically and mentally degraded and then sentenced to be executed. He dies on the cross, giving himself up as the last sacrifice for every sin ever committed, or ever to be committed. From Luke 24:
[44] And he said unto them, These are the words which I spake unto you, while I was yet with you, that all things must be fulfilled, which were written in the law of Moses, and in the prophets, and in the psalms, concerning me.
[45] Then opened he their understanding, that they might understand the scriptures,
[46] And said unto them, Thus it is written, and thus it behoved Christ to suffer, and to rise from the dead the third day:
[47] And that repentance and remission of sins should be preached in his name among all nations, beginning at Jerusalem.
[48] And ye are witnesses of these things.
The old covenant was broken, and the new one began. After Christ had died anyone who believed in him, believed that God had sent his only son as a sacrifice for mankind’s benefit, and asked for forgiveness for any sin (whatever it was) would be given it. The whole point of Christianity was the rejection of the legalistic Jewish texts and way of life, and a new church comprised of people who believed, wanted to be good people and do as Jesus commanded - love your fellow man. As such they experienced their own persecution by the Jews (who saw them as “heretics”) and the Romans (who saw them as dissenters). Fair dos, thought the members of the original church, Christ suffered horribly and hadn’t even done anything to deserve it, so what we’re going through is nothing. AND we get to go to Heaven for ever afterwards because of his sacrifice, so I love Jesus and God no matter what happens to me, even if I die. Hence the New Testament, full as it is of stories of matrydom in the face of persecution. In the decades following Jesus’s death the disciples and the early church began to commit what they had seen and heard from Jesus to writing as they were drawing to the end of their lives and wouldn’t be able to pass on their stories to new members - hence the written gospels.
Flash forward two thousand years and we have a (fundamentalist) religous class damning to Hell all those who will not follow the literal word of God as found in the Bible (ever letter of every word of it divine and straight from God, don’t you know) and saying “forget this whole hugging each other and being nice crap, if we have to kill every gay out there to make sure marriage remains sacred then I say ‘Bring me my sword and I will bathe this world in blood in the name of the Lord!’”. The same people are also not too hot with people questioning them or anything they say, and shouting down anyone who says the Bible (including the whole redundant Old Testament) isn’t a literal intruction manual for true believers to follow. They’re also quite clear that the book of Leviticus should be followed in its entirety - no masturbation, no adultery, no divorce, no laying with another man as you would with a woman…
Southern Baptist Preacher: “What? Yes I know it says you can’t eat shellfish on Friday in there but we can ignore that because that’s just silly, now get out there and collect some tithes!”
Funny how history repeats itself…
Hopefully that makes clear what Jesus changed, and why.