What is the Biblical definition of love?

Love is categorized by different expressions, most notably agape — a Greek word for the love that is part of the essence of God (1 John 4:8, 16). Agape is not an emotion or a feeling, but a divine passion for the ultimate good of men that is active, sacrificial, and unconditional. It is not based on the goodness or integrity of the object of love, but on the goodness and integrity of God. This love is the greatest commandment (Matt. 22:37–40; Rom. 13:9–10), the greatest motivator (2 Cor. 5:14–15), and the most enduring power in the universe (1 Cor. 13:8).

For the believer, love for God is personal love based on His virtue. This love is expressed through a lifestyle of loving God, which means guarding, preserving, and treasuring His Word (John 14:15). The love of Christ—God's eternal love manifested through Jesus and produced by the Holy Spirit—is the only force that can motivate believers to fulfill their commission (Rom. 5:5; Gal. 5:22).

Love for others is unconditional love based on the virtue of the one loving. This is demonstrated through simple thoughtfulness and courtesy, and is the result of a relaxed mental attitude made possible by biblical hope (1 Cor. 13:13; 1 Pet. 1:12–23). The highest expression of this love is loving those who are absolutely unlovable, a work that is impossible apart from the Spirit of God.