Though the most common references to “keep” have to do with maintaining an object in one place or in ones presence, the Bible refers to it in several relational ways. To keep a promise to your brothers and sisters (1 Samuel 18:1-4), it is mentioned in a prayer that “the Lord will bless you and keep you” (Numbers 6:24), to keep watch for the Lord’s coming, (Luke 12:37) or “to keep in step with the Spirit (Galatians 5:25) are just a few.
The ancient book of Genesis tells a story of a brother who refused to keep this unwritten law of God. In it, Cain and Abel work in their own ways to please the Lord; Abel kept sheep and Cain grew crops. They both chose and presented first fruits of their labor, their common goal being to please their God. The Lord was pleased with Abel’s offering, but was not pleased with Cain’s.
Cain was furious and he let everyone know about it. The Lord than counseled Cain, saying, “Why are you angry? Why do you look so sad, depressed and dejected? If you do well, will you not be accepted? And if you do not do well, sin desires to bring you down; but you can, and must, master it.”
Than Cain said to his brother, “Let’s take a walk.” When they were in the field, Cain raised his arm against his brother, bringing it down upon Abel, killing him.
The Lord than asked Cain, “where is Abel, your brother?” He angrily replied, “I don’t know and I don’t care. Am I my brother's keeper?” The Lord asked, “What have you done? The voice of your dead brother is crying to Me from the grave.”
In his song “Brother’s Keeper”, the late Rich Mullins further describes what it means to truly keep our brothers and sisters.
Now the plummer's got a drip in his spigot
The mechanic's got a clank in his car
And the preacher's thinking thoughts that are wicked
And the lover's got a lonely heart
My friends ain't the way I wish they were
They are just the way they are
And I will be my brother's keeper
Not the one who judges him
I won't despise him for his weakness
I won't regard him for his strength
I won't take away his freedom
I will help him learn to stand
And I will ~ I will be my brother's keeper.
The crowd asked him, “Then what are we supposed to do?”
“If you have two coats, give one away," he said. "Do the same with your food.”
Luke 3: 10-11