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Born in the Fullness of Time

Brian Arnold
December 15, 2021

Have you ever wondered why Jesus came when he did? Why didn’t the Father send Jesus just after Adam and Eve sinned? Or why not in 500 BC or 500 AD? Why send him around the year 4 BC?

In writing to the Galatians, Paul slips in an interesting argument for Christmas:

But when the fullness of time had come, God sent forth his Son, born of woman, born under the law, to redeem those who were under the law, so that we might receive adoption as sons. (Gal. 4:4–5, emphasis added)

Paul claims that Jesus was born at the fullness of time. What did he mean by this? Part of the answer is that God was waiting for sin to fill up. Paul even argues that God gave the law to increase sin, so that grace could outpace sin (Rom 5:20–21). One early letter after the New Testament, the Epistle to Diognetus, answers the question of God’s patience with sin this way:

God permitted us in the former time to be carried away by undisciplined impulses...led astray by pleasures and lust, not at all because he took delight in our sins, but because he was patient; not because he approved of that former season of unrighteousness, but because he was creating the present season of righteousness, in order that we who in the former time were convicted by our own deeds as unworthy of life might now by the goodness of God be considered worthy, and, having clearly demonstrated our inability to enter the kingdom of God on our own, might be enabled to do so by God’s power. (Ep. Diog. 9.1)

Had Jesus come right away, we never would have understood the sinfulness of sin. We would have thought that we could earn salvation on our own, or that we could will ourselves to overcome sin. God was patient and waited for sin to reach the brim.

But other things were happening in the world to make it the perfect time. The table was being set, as it were, for Jesus to come and for Christianity to spread. Over the next two weeks, I want to give you some historical reasons why Paul said Jesus came at the fullness of time. In the next post we'll look at Greek and Roman backgrounds, and then in the final post, we’ll look at Jewish backgrounds.

Together, we’ll marvel at why God sent Jesus at just the right time. I hope that your wonder in God is rekindled as we look at the world’s most important birth, as God sent his Son into the world to rescue us from sin.


Dr. Brian Arnold serves as the fourth President of Phoenix Seminary. In this role, he combines a love for the local church with a passion for serious, academic theology. He is convinced that seminaries are servants of the church, uniquely positioned to train men and women for mature, biblically-grounded ministry in a rapidly changing world.

Before joining the faculty of Phoenix Seminary in 2015, Dr. Arnold served as the Pastor of Smithland First Baptist Church in Kentucky. Prior to pastoring, he worked as a paramedic for nearly a decade. Dr. Arnold earned his Ph.D. from The Southern Baptist Theological Seminary in 2013 and has since authored two books, Justification in the Second Century (de Gruyter; Baylor University Press) and Cyprian of Carthage: His Life and Impact (Christian Focus), and a number of journal articles. He has been married to Lauren since 2007 and has two children, Jameson and Natalie.

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