The law say's look to the cross. If the law was sufficient then why did God become a man and die on the cross?
God divorced the House of Israel and according to His own law cannot remarry her. Allow me to explain:
Jer_3:8 And I saw, when for all the causes whereby backsliding Israel committed adultery I had put her away, and given her a bill of divorce; yet her treacherous sister Judah feared not, but went and played the harlot also.
From Isaiah we read
Isa 50:1 Thus saith the LORD, Where is the bill of your mother's divorcement, whom I have put away? or which of my creditors is it to whom I have sold you? Behold, for your iniquities have ye sold yourselves, and for your transgressions is your mother put away.
AND WE READ GOD'S OWN LAW:
Deu 24:1 When a man hath taken a wife, and married her, and it come to pass that she find no favour in his eyes, because he hath found some uncleanness in her: then let him write her a bill of divorcement, and give it in her hand, and send her out of his house.
Deu 24:2 And when she is departed out of his house, she may go and be another man's wife.
Deu 24:3 And if the latter husband hate her, and write her a bill of divorcement, and giveth it in her hand, and sendeth her out of his house; or if the latter husband die, which took her to be his wife;
Deu 24:4 Her former husband, which sent her away,
may not take her again to be his wife, after that she is defiled; for that is abomination before the LORD: and thou shalt not cause the land to sin, which the LORD thy God giveth thee for an inheritance.
Further we understand God's plan...
Jer 31:10 Hear the word of the LORD, O ye nations, and declare it in the isles afar off, and say, He that scattered Israel will gather him, and keep him, as a shepherd doth his flock.
Heb 13:20 Now the God of peace, that brought again from the dead our Lord Jesus, that great shepherd of the sheep, through the blood of the everlasting covenant,
Heb 13:21 Make you perfect in every good work to do his will, working in you that which is well pleasing in his sight
Joh_10:11
I am the good shepherd: the good shepherd giveth his life for the sheep.
AND
Jer 31:33 But this shall be the covenant that I will make with the house of Israel; After those days, saith the LORD, I will put my law in their inward parts, and write it in their hearts; and will be their God, and they shall be my people.
Jer 31:34 And they shall teach no more every man his neighbour, and every man his brother, saying, Know the LORD: for they shall all know me, from the least of them unto the greatest of them, saith the LORD: for I will forgive their iniquity, and I will remember their sin no more.
Heb 8:10 For this is the covenant that I will make with the house of Israel after those days, saith the Lord; I will put my laws into their mind, and write them in their hearts: and I will be to them a God, and they shall be to me a people:
Heb 8:11 And they shall not teach every man his neighbour, and every man his brother, saying, Know the Lord: for all shall know me, from the least to the greatest.
Heb 8:12 For I will be merciful to their unrighteousness, and their sins and their iniquities will I remember no more.
Heb 8:13 In that he saith, A new covenant, he hath made the first old. Now that which decayeth and waxeth old is ready to vanish away.
Heb 10:15 Whereof the Holy Ghost also is a witness to us: for after that he had said before,
Heb 10:16 This is the covenant that I will make with them after those days, saith the Lord, I will put my laws into their hearts, and in their minds will I write them;
Heb 10:17 And their sins and iniquities will I remember no more.
A covenant is a marriage agreement. But God will not break His own law. So God's solution, which was a mystery until Jesus taught it to Paul, "God with us... Emanuel" Came to us and died for us, our Lord and Saviour Jesus Christ (I prefer to call Him Yeshua which means Yah's Salvation). But it doesn't just end there, we too must die to our old nature and be baptized and raise up to a newness of life with Christ.
Only death of God/Yeshua/Immanuel will release us from the Old Covenant and allow us to enter into the New Covenant. God's ways are higher than ours and He is Perfect in all Righteousness.