I feel a bit sorry for Jeremy Corbyn. I think that he's genuinely a man of principle. Which is where his problems start! Because as a politician there are lots of things that you might like to do in principle that are entirely impossible in practice. Either because they cost too much to because you don't have the power to enact them.
Teresa May and the conservatives are in exactly the same boat over their pledges on immigration. They have reiterated the promises of the last Conservative manifesto to reduce immigration to the tens of thousands a year. But it is very unlikely that they will be able to do this because of the nature of our law, international law and the limits of their own power.
This inability to carry out manifesto promises doesn't appear to bother most politicians. What matters is a combination of political values and popular opinion. I don't want to be totally cynical and suggest that parties make policy solely on the basis of what will get them elected. I still think that there are differing philosophies of government that influence their decisions. But I don't want to be naive and suggest that parties don't listen to what the general public wants or believes can be practically carried out. There again, that might well be the problem for Jeremy Corbyn!
The primary way that the Bible explains who God is is by the way that he keeps his promises. He is the manifesto keeping God. The ones who promises to act to save his people, who then carries through on his promise. Jesus is presented in the New Testament as the great promise fulfiller. Time and time again Jesus fulfils the specific predictions of the Old Testament as well as the broad promises of God. To the extent that Paul says in 2 Corinthians 1:20 "For no matter how many promises God has made, they are “Yes” in Christ."
The Lord is the gracious God who makes great promises to His people in love. Promises to be their God and to near leave them or forsake them. Promises to bring them home to enjoy relationship with him forever. Promises to restore a broken and cursed world to the beauty of a new creation.
The Lord is also the powerful God. The one who has never failed to keep his word. The one with the ability to carry out all he has promised.
It's important that we way up the promises of the politicians as we think about who to vote for. But they will always fail to keep them. That's why it's even more vital that we depend on the promises of God in Christ. Because he has always delivered and he will continue to do so.