The Law of God is eternal. And unchangeable. Anyone who breaks it can not be spared.. On Mount Sinai God describes Himself to Moses as One "that will by no means clear the guilty..." Exodus 34:7.

God governs a moral universe, where all intelligent creatures must abide by a common standard that He has set. This standard is for the safety, peace and wellbeing of everyone. The 10 commandments is that standard. It is the standard of character for all creatures.

Countries have laws and these laws ensure the peace and safety of everyone. By forbidding certain acts like stealing, murder etc these laws protect the citizens from being hurt, exploited or taken advantage of by others. Everyone's happiness and prosperity depends on everyone adhering to these laws. If anyone breaks any of these laws, they must be put away in jail because they've disturbed someone's peace and caused pain and distress.

The universe of God works the same way.

The Law of God governs over all. And all must adhere to it so all can be peaceful and happy. Anyone who breaks this Law will be put away. Meaning God will take back the life that He gave that person, as God clearly explained to Adam and Eve, "But of the tree of the knowledge of good and evil, thou shalt not eat of it: for in the day that thou eatest thereof thou shalt surely die." Genesis 2:17.

But to Heaven's dismay, Adam and Eve went right ahead and ate the forbidden fruit anyway. Breaking God's Law. And the penalty of death was pronounced on us all.

When mankind broke the Law, God, consistent with His character as a just God, punished man with everlasting death. Says Paul, "For I, through the law, am dead to the law". Galatians 2:19.
Meaning as far as the Law of God is concerned, he's a dead man. We're all dead men.

God can not spare anyone who breaks His Law without jeopardizing the peace and order of the universe. The lawbreaker must be brought to book. Or else everyone everywhere will lightly regard God's Law. Unless the promised punishments are enforced, those who haven't sinned will think God is a God of empty threats and the whole universe will devolve into chaos. So it was imperative that Adam and Eve die. That their sons die. That our own forefathers die. That me and you and our relatives and friends die. That everyone born of a woman die. So angels and all other intelligent creatures across the universe may see that breaking God's Law indeed has consequences.

But then again, God is a God of mercy:

He describes Himself to Moses as “The LORD, the LORD, a God merciful and gracious, slow to anger, and abounding in steadfast love and faithfulness, keeping steadfast love for thousands, forgiving iniquity and transgression and sin..." Exodus 34:6,7.

How is a God who forgives inequity and transgression and sin also a God" who will in no wise clear the guilty"?

Because of a plan engineered at the creation of the world. And put in motion as soon as Adam and Eve broke the Law. This is the plan of Redemption.

The laws of any country are equal to the people of that country since it is the people who elect the leaders. Any law in any country can change overnight if people want it to change. Someone can commit the most heinous crimes, but if the masses don't want that person arrested and they show their power, that person won't be arrested. The power of government is always in the hands of the people. The people = the law.

But in the universe, God = the Law.

The Law is equal to God and God is equal to the Law. Anyone who breaks the law of God can only be saved by God who is equal to the Law. God is the Judge. And only God can be the Savior.
When mankind sinned, only God could come to our rescue. Not angel. Not cherub. Not seraph.

Because mankind had been given life but forfeited it by breaking the Law in the Garden of Eden, God gave us a second chance by giving us Jesus.

Jesus is the Messiah who was born to live a blameless life on behalf of men that any man can take that blameless life and present it as his own before God. Says Paul, "I am crucified with Christ: nevertheless I live; yet not I, but Christ liveth in me: and the life which I now live in the flesh I live by the faith of the Son of God, who loved me, and gave himself for me." Galatians 2:20.
In the Plan of Salvation, Jesus lives a life that pleases God, God makes that life available to us that we can claim it and be judged as never having broken the Law. The life of Jesus becomes like something we cover ourselves with so when God looks at us, He sees only the perfection of Jesus. Not our own failure.

Jesus illustrated this in the parable of the wedding banquet where a father threw a wedding feast for his son and all guests wore a wedding garment that was supplied, but one unruly guest wore his own garment. The father asked him, "Friend, how camest thou in hither not having a wedding garment? And he was speechless." Matthew 22:12.
The wedding is the kingdom of God. The wedding garment is Christ's righteousness. This garment is to be supplied, meaning the righteousness must be supplied. None can bring their own righteousness because "all have sinned and fallen short of the glory of God", Romans 3:23.

Yet Jesus living a blameless life on behalf of us was only half of the Plan of Redemption.

God had declared to Adam, On the day that you eat of the fruit of the forbidden tree you shall die. And Adam having done exactly that, God had no choice but to carry out the death sentence of the human race to satisfy the demands of the broken Law that wanted the blood of the sinners. Now, Jesus, as the Messiah didn't stop the execution of mankind, instead he took mankind off the hook AND PLACED HIMSELF IN MAN'S PLACE. In the language of the streets, Jesus took a bullet for us.

The death penalty of the human race went ahead as the Law demands, but God, the Lawgiver Himself suffers the penalty in the person of Jesus at Calvary.

"The wages of sin is death" Romans 6:23. Fortunately for us, consistent with His character as a merciful God, God chose to suffer the penalty of death HIMSELF so that mankind can go free. Heaven takes upon itself the punishment meant for a fallen world so the fallen world can get a second chance With Heaven. Punishment is served, but a merciful God, in the person of Christ, suffers on behalf of the guilty.

Justice is served but also mercy is shown.

Justice and Mercy - two opposing forces - meet and harmonise in the Plan of Redemption. David renders this in a more poetic language, "Mercy and truth are met together; righteousness and peace have kissed each other." Psalms 85:10

And Isaiah, looking forward to Christ's sacrificial death that would satisfy the legal claims of God's broken Law, setting the guilty race free, he says, "Shall the prey be taken from the mighty, or the lawful captive delivered? But thus saith the LORD, Even the captives of the mighty shall be taken away, and the prey of the terrible shall be delivered: for I will contend with him that contendeth with thee, and I will save thy children." Isaiah 49: 24,25.

Mankind, the rightful prey of Satan who they chose when they disobeyed God, a doomed race under the curse of the Law they broke whose penalties they can't escape, finds relief through Christ's offer to live a blameless life on their behalf and to also die in their place. Thus the lawful captive goes free. The law itself remains unchanged. And as strict as ever.

This is the plan of Salvation.

Where God can be a just God, and yet the justifier of all who believe in Jesus Christ. Roman's 3:26.
"For the wages of sin is death, but the gift of God is eternal life in Christ Jesus our Lord." Romans 6:23.