No, we don't spill the blood of our fellow brothers and sisters in Christ. (At least, I hope that none of us have.) But at times we behave in ways that can injure them both intellectually and emotionally. That is why Paul drives home the point in Hebrews 13:1, "Let brotherly love continue."
We need each other. If a man says, I love God, and hateth his brother, he is a liar; for he that loveth not his brother whom he hath seen, how can he love God whom he hath not seen? (I John 4:20) Pretty heady stuff right there. Our religion is based on the love of God--him for us, and us for him. How then is it possible to love one (God) and not the other (our fellow believers)?
Clearly God intends for us to treat each other like family. We may not be related here on earth but we are related through the blood of Christ. The New Testament many times over has referred to the brethren, and, called believers brothers and sisters. A look into Romans 8:16,17 tells us that not only are we brethren, we are joint-heirs with Christ.
Accepting that to be true, the realization that we love our brethren becomes a part of our witness and testimony that Christ has made a difference in our lives. So much so that we are bound together like family. Pastor Josh said in Sunday's sermon that love is the gasoline that fuels faith. Love is also a fruit of the Spirit along with joy, peace, longsuffering, gentleness, goodness, faith, meekness, and temperance (self restraint). If we live in the Spirit, those are the outward signs of who we are.
God is love. And, so, love should define us as Christians. I Corinthians 13 devotes itself to the importance of love in all that we do. It begins, "Though I speak with the tongues of men and of angels, and have not charity (love), I am become as sounding brass, or a tinkling cymbal. And, ends with "And now abideth faith, hope, charity, these three; but the greatest of these is charity (love)." If we all acted accordingly, what a difference this world would be. Yes, we are our brother's keeper.