1 John 4:12

No one has ever seen God; but if we love one another, God lives in us and his love is made complete in us.

(v12, NIV)

There is much talk about abiding and living in someone in 1 John. Another example is here where by loving one another, God lives in us. This love we show to others is an outpouring or result of God's love for us. In addition, it does not originate from us, but it originates from God. God is love and he shows us love through his son Jesus Christ. By loving one another, we prove that God lives in us. It also seems to be the idea of God among us when in reality we cannot physically see God. John points this out at the beginning of the verse: no one has ever seen God. However our act of loving one another proves and shows God living in us.

There is also this aspect of completeness. John ends this verse and paragraph by saying that his love is made complete in us. This completeness is being referred to loving one another. Love is not complete until we love one another. Love is only in part or partial if we are not giving love. If we only receive, it is not complete. Love is made complete when we love one another. It's like a cycle and the cycle is not complete if it stops with you. When you receive love, we birth a passion and desire to love others. By doing so love is made complete in us.