Sjaak, Jesus does go on to give a lot of commandments after he says that about being the least in the kingdom of heaven.

But he also says things like this in that sermon:

29 And if thy right eye offend thee, pluck it out, and cast it from thee: for it is profitable for thee that one of thy members should perish, and not that thy whole body should be cast into hell.

and:

"Be ye therefore perfect, even as your Father which is in heaven is perfect."

I believe you have to understand that whole sermon as Jesus showing those he was speaking to, and also us, that there is no way we are going to make the cut with our own righteousness. I believe he was paving the way to the coming good news which would be He himself dying on the cross so the justice of God would be satisfied and sinners could be saved. Galatians, Romans, etc. are all about how we can't be saved by the law. But Jesus was still preaching under the law at that time when he gave that sermon. No God doesn't change, he is the same yesterday, today and forever but his plan of redemption involved bringing a New Covenant, which would make the Old Covenant obsolete.

And that last part there is important for you to come to understand. The New Covenant is very different from the Old. The Gentiles were never told to keep the Sabbath, or refrain from eating pork, etc. And contrary to what you say, there is evidence that the food laws did change. The Sabbath, food laws, etc. were shadows of things to come. The substance is Christ. He fullfilled the law. Believers are lead by the Holy Spirit, and not the written code, the laws are written on our hearts, but not laws like the seventh day Sabbath and dietary laws, which were again, just shadows pointing to Christ. He is our Sabbath rest. And our salvation is spiritual, not physical, so what food we put in our bodies no longer defiles us. And no I don't agree that the Sabbath changed to Sunday. That's a false teaching that's caused all kinds of confusion. But in Christ we rest from good works to save us. He is our eternal rest. But Christians desire to do good works. We are his workmanship, and we walk in the good works he has prepared for us beforehand.

I'm writing all this off the top of my head so sorry if I get some words wrong on some of these scriptures I'm trying to remember. I don't have time to look them all up and I'm sure you probably know them all.

And even if you don't agree with anything I'm saying, I write these sermons out every so often just to do it I guess. Maybe it will help someone else if you disagree with it all.

But I do think your problem, at least one of them, is in not understanding the New Covenant and what all that means. I grew up as a Seventh Day Sabbath keeper and kept all the dietary laws, observed the Holy Days, etc. and I do not believe I was a Christian at all at that time. I didn't even really know who Jesus was at all. It was all about earning my own righteousness. I still don't eat pork or other unclean meats to this day. Growing up we were taught that it was completely disgusting to eat unclean meats, we were defiled if we did, and I guess it's hard to get past that. It still kind of repulses me to even smell it. I find myself getting irritated when my husband fixes bacon. lol But I don't think it's sinful for him to eat it. Just can't bring myself to do it. But not keeping the Sabbath does nothing to my conscious. I feel completely free of that, knowing my rest is in Christ, always, every day, and forever.

The Pharisees were known to be very righteous by the jews. And they were outwardly. So when Jesus said that, I'm sure the jews thought, "how can we be more Holy than the Pharisees?" but we know Jesus also told the Pharisees they were white washed tombs, etc. inwardly. So what did he really mean by saying "unless your righteousness shall exceed the righteousness of the scribes and Pharisees, ye shall in no case enter into the kingdom of heaven?" I think he wanted them to understand it was impossible apart from the good news that Christ would die and his righteousness would be imputed to them by grace, through faith. That's how they could also be perfect, as their father in heaven was perfect, which he later said they must be in that same sermon.

Okay, I'm done. Sorry for the sermon! But if you decide to try to gain eternal life based on the Sermon of the Mount, good luck!