1 John 3:1-3: a child of God

How great is the love the Father has lavished on us, that we should be called children of God! And that is what we are! The reason the world does not know us is that it did not know him. 2 Dear friends, now we are children of God, and what we will be has not yet been made known. But we know that when he appears, we shall be like him, for we shall see him as he is. 3 Everyone who has this hope in him purifies himself, just as he is pure.

1 John 3:1-3, NIV

The word used for God's love in the New Testament (agape) is often referred to as unconditional love. Apart from God's revelation, it is more like the love that the first century society would expect a servant to show one's master. In human relationships probably the best example of an authority figure showing this kind of love is the love of parents for their children.

We might picture ourselves showing an impartial
(Deuteronomy 10:17-19; Acts 10:34-35; Romans 2:11)
love helping people who are unlovely. We might see giving food and clothing to someone who is dirty, smelly, and desperately poor. But this does not picture the full extent of God's love. Besides being an unconditional love it is an inconvenient sacrificial love. It is as if someone sees a dirty and unruly child living on the street scavenging for food and tells the child, "Come with me, you're going to be my child." It is the kind of love that takes the responsibility for the child, for such things as food and clothing
(Matthew 6:19-34)
, discipline
(Hebrews 12:1-13)
, encouragement
(Philippians 2:1-4)
, education
(Luke 12:11-12; John 14:26; 2 Timothy 3:16; 2 Peter 1:19-21)
, and security
(Psalm 23:1-6; Romans 8:28-39; 2 Timothy 1:12)
Jesus said the kingdom of God is made up of people who are like little children
(Matthew 18:1-4; 19:14; Mark 10:13-15; Luke 18:15-17)
. Paul described the Holy Spirit we have received
(Romans 8:9)
as crying out within us, Abba, Father."
(Romans 8:15-16; Galatians 4:6)
Abba is the Aramaic term for "the father" meaning "my father" or "our father". This was the term that the Jews would use in Israel during the first century. Because of the simplicity of its syllables, Abba is also the term a baby would use for father. Crying out is what small children do. Thus, Paul's picture is that, through the Holy Spirit within us, we cry out to God as small children cry for their fathers.
God adopting us as His children through the sacrifice of Jesus Christ shows us the graciousness of God's love in a way that we as Christians often forget. Rather than resting in the security of being God's children, we worry about food and clothing, become discouraged, and worry about whether we are doing the right thing. We need to acknowledge the responsibility God has taken on in ours lives by making us His children. For us to return to our previous lifestyle would make as much sense as a child living on the street answering the offer of a rich family, "Yes, I want to be your child, but I want to keep living in the street begging for food and digging in garbage." For God, the perfect Father, to forsake us, would make as much sense as good parents forsaking their children
(Matthew 7:9-11)