One of the characteristics of a Christian is that of unity with other believers. The Lord considered this so important that it is one of things that He prayed for before He was crucified.
John 17:22,23 The glory which You have given Me I have given to them, that they may be one, just as We are one; I in them and You in Me, that they may be perfected in unity, so that the world may know that You sent Me, and loved them, even as You have loved Me.
It is pleasant to us and pleasing to the Lord when we dwell together in unity. Notice that the Word says to dwell together. The Lord has called us to be in community with each other.
Psalm 133:1 Behold, how good and how pleasant it is For brothers to dwell together in unity!
The Lord says to put on love which is the perfect bond of unity. Love is to characterize us as Christians. Love is considering someone else more important than ourselves.
Colossians 3:14 put on love, which is the perfect bond of unity.
The source of our love for others is not the person that we are seeking to love but God. When we are filled with the Lord and His Spirit then we will be filled with His love for others.
Galatians 5:22 But the fruit of the Spirit is love, joy, peace, patience, kindness, goodness, faithfulness,
It is by our love for one another that people will know that we are Christians and are His children.
John 13:35 By this all men will know that you are My disciples, if you have love for one another.