1 Peter 1:23

23 for you have been born again not of seed which is perishable but imperishable, that is, through the living and enduring word of God.

Here Peter is telling them that their sincere love for others is certainly possible, since they now have a new life. This new life comes from an imperishable seed; that which is planted in them by the Holy Spirit and through the living Word of God (which is actually Christ, see John 1:1).