The word for love in 1 John 3:11 does not refer to a sentimental love but is a strong word that describes God. It is the kind of love that recognizes a need and responds to that need.
An illustration of this contrast is seen in the case of Cain, who was of the Wicked One and killed his brother (v. 12). He killed Abel because his own works were evil and his brother's were righteous.
Cain did not have love in his heart because he was not a child of God. He had hatred, and for that reason he murdered Abel.
First John 3:16 shows that true love is climaxed by our being willing to lay down our lives for fellow believers. This is the very opposite of being willing to slander and spread evil reports concerning God's children.
This kind of love is very practical, for John said, "But whoso hath this world's good, and seeth his brother have need, and shutteth up his bowels of compassion from him, how dwelleth the love of God in him?" (v. 17).
God expects us to share the temporal and spiritual provisions that He makes for us. How can anyone, looking on this lost world, say that he loves the Lord and yet not seek to make known to the unsaved the unsearchable riches of Christ?
Because the Scriptures say that no murderer has eternal life abiding in him, we need not conclude that a murderer cannot be saved. He can be if he will come to Christ and receive Him as Saviour.
"By this shall all men know that ye are my disciples, if ye have love one to another" (John 13:35).