David wrote that a righteous man is one who "swears to his own hurt and does not change" (Psalm 15:4). These words go beyond the righteous man. They describe God. Even when the cost is off the charts, God keeps his promises. In Gen 3:15 he promised a Savior. In 2 Sam 7 he added the promise of a Messiah-King. Even when it meant infinite hurt (the crucifixion and rejection of his Son), God did not shrink back from his promises. He was faithful. This is what Paul meant in 2 Cor. 1:20 "For all the promises of God find their yes in him [Christ]."
God's promises promise eternal life to those who believe (Rom. 10:9), the physical return of his Son (Acts 1:9-11), new Heavens and Earth (2 Pet. 3:13), eternal "destruction" for those who do not obey the gospel (2 Thes. 1:7-9) as well as a host of other promises.
When tempted to doubt the promises of God meditate on the cross. When tempted to compromise your own promises, meditate on the cross. God promised our redemption and even though it cost him his Son to fulfill those promises, he did not change.
The fact that God keeps his promises does not mean your life will be easy. It may be hard, but another promise is clear. “All things work together for good to those who love him, to those who are called according to his purpose” (Rom. 8:28).
Our God is a promise-keeper. Trust Him!