"The saints will not commit spiritual adultery to go back to the Law"
This is true, the law can't save anyone all are save by faith in Jesus, He is the only way to be saved.
The law holds us all guilty as sinners. So if we try to be saved by it we will fail.
Jesus kept it and was free from sin, so death had no hold on Him. Death has a hold on all of us.
The law points out sin
grace over looks sin
Jesus didn't come to destroy the law he came to give us a way to be free from the law.
To keep the law to be saved is wrong.
To keep the law because you hate sin or hate dong what is wrong is not spiritual adultery.
If a husband said to his wife if you love me please obey me and the wife said i love and she tried to obey him would that be adultery?
Exo_20:6 And shewing mercy unto thousands of them that love me, and keep my commandments.
Deu_11:1 Therefore thou shalt love the LORD thy God, and keep his charge, and his statutes, and his judgments, and his commandments, alway.
Joh_14:15 If ye love me, keep my commandments.
Joh_14:23 Jesus answered and said unto him, If a man love me, he will keep my words: and my Father will love him, and we will come unto him, and make our abode with him.
Joh_15:10 If ye keep my commandments, ye shall abide in my love; even as I have kept my Father's commandments, and abide in his love.
1Jn_5:2 By this we know that we love the children of God, when we love God, and keep his commandments.
1Jn_5:3 For this is the love of God, that we keep his commandments: and his commandments are not grievous.
Your picture separates Jesus and the law but the Bible teaches us that Love for Jesus obeys the law. Jesus perfectly obeyed the law and when i love Jesus i naturally show it by desiring to obey Him.