One of the most difficult balances in the Christian life is the understanding of salvation by means of obedience or by means of free grace. Piper points out what Christ meant when He said, “If you love me, you will keep my commandments” (John 14:15).
Jesus… was describing the effect of love, not the essence of love. First there is love, then there is the effect – obedience. The obedience is not identical with love.
(When I Don’t Desire God, 34.)