laws and decisions, what are they based on anyway?

An excellent question has arisen here to say the least!

Heinrich Himmler, who was at one time Adolph's Hitler's second in command, believed firmly that the laws the Nazi German government instituted were inspired by his God. Heinrich Himmler's God was reflected by many of the ancient pagan prophecies which were dormant in Germany before the rise of Nazism. Himmler and Hitler wished to strip the "Christian Veneer" off the German people and return their entire culture to what we in Christendom would call the occult and paganism. Many people who were active in the "faith" of Nazism believed they were restoring to the earth the true race of "God Men." Some of the SS soldiers had their belt buckles engraved with the words (in German, of course) "God is with us," as they worked diligently at slaughtering six million Jews and countless others.
I mentioned that to say this: That we can be assured that just laws will bear the pleasant fruit of righteousness. Mercy and judgement will embrace each other there. These laws will proceed out of and from the inspiration of the One True God. I firmly believe that the One True God is the God of the bible. We have far too few of His laws, precepts, and standards instilled in our culture here in the United States.
Evil and unjust laws will always proceed out of wickedness and could be based on a multitude of precepts, standards, etc... and can arise from humanism, occult beliefs, paganism, and a multitude of other wicked devices labeled in a manner to deceive us into believing they are good and which are actually oppressive, manipulative, or self serving for some special interest person or persons.
Even if the "Lawgivers" themselves claim to be inspired by God, wickedness is still wickedness -- Is this not one of the basic commandments? Not to take the name of the Lord thy God in vain? e.g. We see the slaughterings of the godly during the inquisitions, which were done in the name of god and authorized by law.
We see laws and mores in some Eastern cultures that allow for honor killings of family members. The presumed lawgivers of these laws claim to be inspired by their god and their holy texts.
Yet the hope we have is righteousness is still righteousness, God's mercy is still God's mercy, His justice is still true and without partiality. Let us pray for our leaders and law givers that their hearts will be truly opened by the God of Abraham, Issac and Jacob who is even Christ; thereby instilling God's true attributes into our country wherever that country may be wherein we each are found.

I am inspired by reading the story of the rebuilding of Jerusalem and the temple how pagan kings were used by God to fullfill his purposes.

All it took was faithful men to be on their knees praying for the fullfillment of his promises.

Yes! Your comment ZekeO has caused me to remember that without the horrible suffering under pagan governments the Jewish people have endured perhaps there would not have been the burning desire in their hearts to return to their own homeland and reestablish the nation of Israel; which has now set the stage for the fulfillment of other prophecies and the soon coming return of our Lord the King and His one thousand year reign.

(Pro 21:1) The king's heart is in the hand of the LORD, as the rivers of water: he turneth it whithersoever he will.

Even the most wicked of rulers and the most wicked of laws God uses to ultimately fulfill his purposes. How great is our God in that He uses the wickedness of this world to destroy the wickedness of this world. When Gideon marched at God's command God caused the enemies of Israel to be blinded with confusion and destroy each other!

Jdg 7:20 And the three companies blew the trumpets, and brake the pitchers, and held the lamps in their left hands, and the trumpets in their right hands to blow withal: and they cried, The sword of the LORD, and of Gideon.
Jdg 7:21 And they stood every man in his place round about the camp: and all the host ran, and cried, and fled.
Jdg 7:22 And the three hundred blew the trumpets, and the LORD set every man's sword against his fellow, even throughout all the host: and the host fled to Bethshittah in Zererath, and to the border of Abelmeholah, unto Tabbath.

All legitimate law is founded in love, just as Jesus summed up the law and the prophets with His profound acknowledgement that loving God with one's whole heart and one's neighbor as one's self essentially fulfills the law.

When laws and decisions are made that are outside of the best interests of the people, we can call that tyranny. We live with a lot of it.

But the law of God is the transcript of His own character. What He requires of us is for our own highest interest and the high interest of those around us. He cannot and will not make any laws that are otherwise, nor will He require anything of us we cannot do. With due apologies to the "sinful nature" believers among us, there are no scriptures that give us any excuse to sin. Again, to command any law that cannot be obeyed is just more tyranny. I contend that tyranny is simply not the character of God.

Deeply imbedded in our human ways is the notion that someone else is to blame for my sins.

We hear it all the time, "Well, nobody's perfect," or "The devil made me do it," or "This is just the way God made me. I sin every day."

Excuses. Useless to God, useless to you.

Quite frankly, I never even really knew God when I lived and thought like that, and I truly did live in those ideas. It was when I broke and confessed that I had committed the sins, I knew better but chose my way over His, that I had no claims, no excuse for my rebellion, that He heard me and accepted me, forgave me.

The law slew me because it was just and right, I was not. The atonement was not God's apology to poor sinful little me for His error of making me a sinner. It was rather the provision of His love, a way to forgive while maintaining the integrity of His law and His obligation to reign righteously over all His moral creatures.

Mercy cannot triumph over justice without a legal provision to set aside the demands of the law. The death of Christ is a very big deal, but it only applies for those who acknowledge their guilt, repent from their wicked ways, and receive the atoning death of Christ as their own death, fully deserved for rebelling against the law of God.

To come away from that still living in the sin of former days- no. Such ones have yet to deal honestly with the Holy One.