Why does God love us? Simply put, because that is what and who He is (1 John 4:8, 16), just as what you are directs your actions. What He does in loving us can be measured by its “breadth, and length, and depth, and height” (Ephesians 3:18).
Love leads people to make things. The same is true of God. Thus “the LORD He is God: it is He that hath made us, and not we ourselves” (Psalm 100:3). More than that, His love leads Him to redeem those who have removed themselves from this intimacy. The Bible says at least twice that this is why and how He redeemed Israel (Deuteronomy 7:8; Isaiah 63:9). And furthermore, in Jesus He bent down and redeemed all who were caught in the web and curse of sin (Romans 3:23-24; 5:8; Galatians 3:13).
Why does He ask us to love? Because He wants us to enter into His joy (Psalm 5:11; John 15:9-12). Because He wants us to be like Him (Genesis 1:27; 1 John 3:1-3; 4:19). He enables and empowers the very possibility of love by simply and enormously loving us. He then asks us to respond in kind, to love Him back, and to pass it on, to love one another with the same kind of unselfish love. The fact that He has to ask speaks not of the weakness of His love, but of the damage the loss of love has caused us. But what He asks, He does, and what He commands, He enables, all by His love, which expresses who He is.
The main expression of love is in giving.
His love is designed to operate in a reciprocal fashion. You know how that works. Someone who truly loves is hoping for love in return, not in a selfish way, but in a joyful way, longing to draw the other into a freely-given, responsive love. Love simply desires others to share its joy. God’s love naturally looks for love.
The main expression of love is in giving. “God so loved the world, that He gave” the best He had to give (John 3:16). As creatures, in order to give we must first receive, but the purpose of receiving is simply to have something to give. Therein is the joy, the greater blessing of giving (Acts 20:35).
What is the cost of love? This would be a strange question if we lived where only love exists. But in the work of love to fill the voids where it is missing, it will experience pain. In loving the unloving, love experiences the pain of their lack of love, in identifying with their hurt, and especially in enduring the pain of loving without being loved in return.