Thank you for the interpretative question, “What does it mean in Isaiah 59:2 that sins separate us from God?”
The word, separate, means to divide, to have a gulf in between. In other words, there is a wide gap that one is walking one direction and the other party is walking in the opposite direction. There is the lack of agreement or oneness.
As one reads Isaiah 59, here are some thoughts for one’s consideration on the separation between Go and the Jewish people.
A. God is the being that is keeping the covenant with the Jewish people. God is not violating or breaking his covenant with the Jewish people.
B. The Jewish leaders and people for the most part have walked away from the covenant made at Mount Sinai (Exodus 20). In verse 3–8, God lists the violations of the Jewish people.
Isaiah 59 says this in part, “Their deeds are evil deeds, and acts of violence are in their hands. 7 Their feet rush into sin; they are swift to shed innocent blood. They pursue evil schemes; acts of violence mark their ways. 8 The way of peace they do not know; there is no justice in their paths. They have turned them into crooked roads; no one who walks along them will know peace” (NIV).
God is calling his people to repentance, to turn around and walk back toward him. The people are stubborn and stiff necked. They keep walking further and further from the LORD God.
C. The separation is a broken fellowship with God, not a rejection by God of his people.
Separation can mean a severe of relationship as to a rejection or abandonment of the relationship liken to a divorce. The other connotation is the relationship exists but it is a fracture one. The Jewish people were still God’s people except that they were not walking according to God’s commandments. There is the lost of fellowship with God. There was the possibility for the Jewish people to repent and turn from their wicked ways and return to God. It is their disobedience, their actions against the commandments of God that set them adrift from God.
One can say as a metaphor that God is the constant and humans are the variables. The person can to align oneself with the constant or deviate from the constant. With each variation, the distance is further apart. It may seem a trite variation, but with each movement the variation increases over time and distance. Before long as a person looks back, if he does, they will realize that they have drifted far from the constant and it will take a change of course to return to the constant. The degree of variance is the separation by the person’s action.
SUMMARY: God is the Constant and man’s decision will affect his alignment to God.
For more perspectives:
https://www.quora.com/What-does-it-mean-in-Isaiah-59-2-that-sins-separate-us-from-God