It may sound trite to say that we are all brothers and sisters, but it’s a truth we have neglected.
If each of us had enough time to do our own genealogy, we’d end up showing the same ancestor at the top of each of our family trees. For there really is only one family tree for the human race, and every family you know is merely a branch on it.
I have been speaking according to physical or fleshly lineage, but the same is true of our spiritual roots. Jesus Christ was designated by God as heir of all creation. As such, we all became His at the coming of His kingdom. Therefore, if each of us were to map our spiritual genealogy, it also would trace back to a common source: Jesus Christ. The only thing is, your spiritual family tree will take far less paper to document than your fleshly family tree. In fact, your spiritual family tree has only you and God. You are directly connected to Him. He’s been tied to you your whole life, even when you didn’t know it.
Therefore, whether we are speaking of our fleshly identity (which ceases when our life on earth is over) or our spiritual identity (which goes on for all eternity), we are still brothers and sisters. God wants us to act like it. We human beings are all family, and that relationship transcends all physical and spiritual differences. There is no reason to call one person a Christian and another something else – we are all Christ’s.