4 You are of God, little children, and have overcome them, because He who is in you is greater than he who is in the world. 5 They are of the world. Therefore they speak as of the world, and the world hears them. 6 We are of God. He who knows God hears us; he who is not of God does not hear us. By this we know the spirit of truth and the spirit of error.
7 Beloved, let us love one another, for love is of God; and everyone who loves is born of God and knows God. 8 He who does not love does not know God, for God is love. 9 In this the love of God was manifested toward us, that God has sent His only begotten Son into the world, that we might live through Him. 10 In this is love, not that we loved God, but that He loved us and sent His Son to be the propitiation for our sins. 11 Beloved, if God so loved us, we also ought to love one another.
As always, the above text, “love one another,” refers specifically to our fellow Christians, not to our unbelieving neighbors or to anyone else outside the Church.
This is the special commandment which Jesus gave to his disciples. It is the sign by which Jesus said others would know that we are HIS.
A new commandment I give to you, that you love one another; as I have loved you, that you also love one another. 35 By this all will know that you are My disciples, if you have love for one another.”–John 13
Yes, Jesus also taught us to love our neighbor (The Second Great Commandment). As E. J. Carnell wrote, “The responsibility to love all human beings is repeatedly set forth with such solemnity in Scripture that an unloving Christian is a manifest contradiction in terms.” (What we today call an oxymoron.)
But when Jesus and John said, “love one another,” they were referring to that unique fellowship we have with all those who believe in Him.