The covenant with Noah guarantees the route. There God promises to maintain his creation. It is the ground on which the track will be laid.
The covenant with Abraham is the track. Its design is displayed in Genesis 12, its first stage is then actually constructed in Genesis 15 and its second in Genesis 17 and 22. There are various more minor stations along the way, but the first stage ends at the city of 'Full Nationhood' - that Abraham will know greatness in having many descendents who will inhabit a promised land. The second stage ends at the city of 'Full Blessing' – that God will be their God so bringing them joy and bringing joy to others through them. These are the destinations. With every station that is passed the train is closer to them and so more goods from those cities are enjoyed.
God owns the railway and has graciously chosen Abraham’s descendents and others to travel in a train driven by various leaders. The requirement is only that in gratitude these people follow his instructions by circumcising their children with all that implies for circumcising their hearts through faith. If not, they will have to leave the train.
The promises begin to progress and the covenant with Moses describes one leg of the journey. The train stops at the station of 'Sinai' and Moses brings the law into the carriage, instructing his passengers on how to behave if they are to remain on the train and if the covenant with Abraham is to be fulfilled. The train continues with various drivers following Moses and reaches 'Full Nationhood.' But as it continues towards ‘Full Blessing,’ the people fail to abide by the law and so the train is stopped at the station of 'Exile' and the people are ordered off. Hope is then given as people repopulate the carriage, but the train only shunts forward another few feet before they sin again. It seems that mere instruction is not enough. The Mosaic leg of the journey is over.
Hope comes now with a new and supreme driver in Jesus. He calls people to get off this train and onto a new one that will run on the same track. In this he promises two things. He will continually remind, encourage and enable people to keep the instructions necessary whilst forgiving them when they fail if they display a genuine desire to remain. He also calls all people to climb on board this train and come with him to 'Full Blessing.'
The passengers of the old one certainly don’t like this. They liked the exclusivity and so question whether Jesus is genuine. And so the arrival of Jesus raises the stakes. They must decide. Will they get on the new train that will move forward or stay on the one that has no further to go? And for everyone else, they must choose whether they want to be on the new train too. Will they trust Jesus promise to take it forward, ever closer to 'Full Blessing' with God that is its goal? Or will they remain where they are and miss out?
As the train moves forward people’s hearts are displayed. Some jump off because they don't like it and refuse to trust or obey the driver. Others jump on for a while but show no real desire to trust and obey him, and so jump off again. Still others are born on the carriage yet jump off in doing the same. But many others who transferred from the previous train, or who jumped on or were born on the train remain. It is they who will reach the final destination.
