I think at some point in all of our lives we struggle with the concept of works-righteousness.
This is the idea that in some way we can earn our salvation. We put all our good works on a divine scale, and we hope they outweigh our bad works. The gates of heaven will open for us if we do enough good things during our lives.
While this is completely the opposite of how the gospel actually works, we still struggle with works-righteousness.
Some people attend church gatherings for this reason. Some people tithe for this reasons. Some business owners give to charity for this reason. Some people look after their neighbors for this reason. We know God expects us to do good things, and so we do them in order to earn merit with God.
In essence, we try to get to heaven on our own. We want to obtain the gift, and we look around at the resources we have available – money, time, energy, desire – and we put them to use in trying to earn the gift.
Sarai was trying to obtain the gift. In this case, the gift was a promised child who would become Abram’s heir and build out a family that would outnumber the stars in the sky and that would bless the entire world.
The child was slow in coming. Sarai was getting along in years, and so was Abram. Time was growing short.
And so Sarai looked around at what resources she had available. Her eyes descended on Hagar. Sarai’s plan was set.
Of course, this wasn’t God’s plan, and it turned out to be a big mess. But God stepped in. That is what he does. Even in our messy situations, he miraculously turns blessing after blessing.
But the point of this story is our human nature not to trust in God’s grace and to try to do it all on our own. This is the fundamental concept of sin. This is why Adam and Eve took the fruit. You might want to read Romans 4 and Galatians 4 at this point.
We cannot earn our salvation. We cannot earn the gift by our own good deeds or smarts or money. We must only trust in God.
This is why it is good news.