Christianity is an odd religion: rather than prescribe some certain set behaviors by which I personally reconcile myself to God or god. My faith is in myself. That is real difficulty of the Bible:

That which many call the difficulty of believing is the essence of self-righteousness. Yes; it is this that lies at the root of, or rather is the root of, this difficulty. Men cling to self as the lad clung to the rope;

Horatius Bonar, How Shall I Go to Good.

There is the difficulty. Christianity is premised upon the work of another man – a man whom I must trust in place of myself.

Deep down in man’s depraved being lies this awful evil, which only God can remove, this determination not to give up self. He deceives himself sadly in this matter, in order to cover his guilt and to cast the blame of his unbelief on God. He holds that he has some great thing to do: though God has declared a hundred times over that the great thing is done! He wants to do the great thing, and to get the credit of doing it; and because God has declared that the great thing is done, “once for all,” never to be done again, he retires into himself, and tries to get up another great thing within himself, by the right doing of which he will please God and satisfy his own conscience. Acceptance of the great thing done is what God presses on him as altogether and absolutely sufficient for his salvation and his peace. But this he shrinks from. He thinks he must wait, and work, and struggle, and weep before he is in a fit state for accepting; and therefore it is that he replies to all the messages from the “ambassadors of peace,” “I can’t.

Faith is a terrifying when it is understood properly. It is complete abandonment of self reliance upon a promise: that God will accept the work of the man Christ of Jesus.

And that is the blessing and wonder of faith. My efforts to reconcile God could never suffice. The nature of the fault between God and humanity is not such as we could resolve.

It was man’s guilt that rendered the cross necessary; for if that guilt remained unremoved, all else would be vain. To be under condemnation would be to be shut out of the kingdom for ever. To have the Judge of all against him in the great day would be certain doom. The cross has come to lift off that guilt from us, and to lay it upon another; upon Him who is able to bear it all; upon Him who is mighty to save. That which should have come upon the sinner has come upon Him, that the sinner might go free. The Judge is satisfied with the work done on Calvary, and asks no more: and when the sinner is brought by the Holy Spirit to be satisfied with that which has satisfied the Judge, the chains that bound the burden to his shoulders snap, and the burden falls, to disappear for ever—buried in the grave of the Substitute, from which it cannot rise.