2 Peter 1:7a says "to godliness brotherly kindness".
Brotherly kindness comes from the Greek word philadelphia and carries the meaning to show love to your brothers and sisters in Christ. This showing of love should come from the heart and not be just meaningless actions. There is a lot to say in the Bible about how we treat our brothers and sisters in Christ.
Matthew 22:37-39 says "Jesus said to him, You shall love the LORD your God with all your heart, with all your soul, and with all your mind. This is the first and great commandment. And the second is like it: ‘You shall love your neighbor as yourself.’"
It is interesting that we can plug all 10 Old Testament Commandments into these two that Jesus gave us. Note that we first must love God with all of our being and then we are to love our neighbors as ourselves. Sometimes I wonder how much the Christian loves himself when I see how they treat their friends with disrespect.
Romans 12:10 says "Be kindly affectionate to one another with brotherly love, in honor giving preference to one another". In other words we need to be showing our brothers love in all that we do. We need to have a genuine concern for our brother caring for their needs and well being.
One of the most compelling verses in the New Testament about loving our brother is found in 1 John 4:20 which says "If someone says, 'I love God,' and hates his brother, he is a liar; for he who does not love his brother whom he has seen, how can he love God whom he has not seen?"
These words speak volumes concerning our love for our brother. What are your actions saying about the condition of your heart?