"For God so loved the world, that he gave his only Son, that whoever believes in him should not perish but have eternal life." (John 3.16 ESV)

The author, John, was a Jew. The audience of the letter to whom John wrote, was for the large part Jews. So I believe John here was referring to the one story that all Jews of his time knew by heart when he wrote "gave his only Son". And that was the story of their ancestral father - Abraham - giving Isaac up as sacrifice.

It was a story of faith and obedience.

And it was a story of God's faithfulness to Abraham, Isaac, and their descendants who kept the faith to the God who called Abraham out.

This promise is also available to everyone who believes in Jesus, in whom there is eternal life.

Happy Easter!