Abraham, Isaac, Jacob and Moses had one big thing in common: faith. They believed the word of the Lord. Completely. They didn't have the scriptures we do now. But they believed God, heard his voice, and loved him.
Jesus did what he did for one reason, and one reason alone: LOVE.
He loves us! Unimaginably so!
And he wanted to be present with us so desperately that he came, lived, suffered, died, and rose again so he could continue to claim the right to forgive, to comfort, to heal, and to SAVE.
To start, he asks that we believe. Only that we believe. That we believe his word above all else. We don't have to earn his love or presence. We don't have to be worthy of him. He paid the price, with his priceless blood, to make us worthy. To cover our sin with his mercy, to forgive our debt. All so we could receive the feast set before us in the presence of our enemies, so we could sit at his table and be filled and satisfied by our extravagant, generous, lavishly-loving God. It is receiving this untold bounty that changes us, that sets us free and heals us deeply, so we can walk out the work he so desperately needs us to do.
In the Hebrew culture, your actions reveal what you believe. If you say one thing and do another, what you did demonstrated the truth of the matter. It is Greek thought/philosophy that divorces belief from action. (And mind from heart, for that matter.) When Jesus said we only had to believe him, he wasn't talking about lip service. It was a radical invitation to walk by faith--to allow living out his word to transform us into the image of God.
Our God never ceases to amaze me.