The Attributes of God: Truthfulness and Faithfulness

This attribute has two sides that turn out to be one thing.
The first is that God cannot lie. Scripture states it flatly in several places. But the attribute says more than that. It also speaks to his completely reliable consistency of character. He is the only true God, and he cannot act inconsistently with himself or with the attributes of his own nature.
Another way of describing the same thing is God's faithfulness - faithfulness to himself, and to everything he has decreed and planned. Truthfulness and faithfulness are not two separate virtues here. Being true to what he says and being true to who he is are the same act.
Paul lands it in a sentence worth sitting with. If we are faithless, he remains faithful - for he cannot deny himself. Look at the reason given. Not "because he is very committed". Because unfaithfulness would require God to be someone other than himself, and that is not available to him.
That is the ground under every promise in Scripture. It does not rest on how well the promise has held up so far.
Scripture links:
- 2 Timothy 2:13 - "if we are faithless, he remains faithful, for he cannot deny himself."
- John 17:3 - the only true God.
- Numbers 23:19 - God is not a man, that he should lie.
He would have to stop being himself first.