While there is a love we should have for all men as our brothers in Adam, here Paul speaks of the special love and affection that exists between brothers and sisters in Christ. There is a fellowship they have with one another based on their common fellowship with God. They share the same love for Christ, the same basic experience of salvation, the same eternal destiny.
And we pray:
LORD Heavenly Father, I in all humility ask Your Essence to gift me with a new level of Love for my spiritual brothers and sisters, O Lord. Let me rejoice in our common Love for You and in all that we share in common. Help me to be kind towards them and to put others above myself. Amen.