The plan fulfilled, the promise kept,
The Christ has come, for man to accept;
Before time was, and space and matter,
The goal was set, by blood and water,
To save mankind in spiritual birth,
Good news to spread in all the earth;
No word of God’s has ever failed:
When to the cross the Lord was nailed,
He struck and crushed the serpent’s head,
In triumph raised from among the dead.
One glorious promise yet remains:
Christ comes to take us to heaven’s domains.

A promise signals a change in situation not evident from the present circumstances. The best promise helps us to visualize not only the present which leaves us dissatisfied, but also the future that will bring great benefits.

The seed is still in the storehouse, isn’t it? And the vine, fig tree, pomegranate, and olive tree have not produced. Nevertheless, from today on I will bless you.
Haggai 2:19 NET

The promise invites faith which has confidence in the one who promised, that within the determined time it will fulfill its word.

The prophets, like Haggai, promised a better future, but the change depended upon the repentance of the people of Israel.

In the same way, today, peace of mind, the presence of God with us, and the heavenly hope all depend upon our drawing near to the Lord.

For who believes that things will get better by themselves?