Many Bible passages proclaim that God is all-powerful, all-seeing, and all-knowing. While God is unlimited by time, space, and matter, His very character has determined that He will never do some things, because to do them would be inconsistent with His nature. One of those things is that God never lies. Not simply because He chooses not to, but because He can't (Hebrews 6:18). It's impossible for Him to do so.
The Bible makes a stark contrast between God and humans with such verses like “God is not human, that he should lie” (Numbers 23:19) and “Let God be true, and every human being a liar” (Romans 3:4). So then, the phrase “God doesn’t lie,” could be accurately restated “God is truth.” God doesn’t possess the quality of speaking the truth; He is the very source of it!
Because of His holiness, when God speaks, He will not and cannot lie. He never deceives; He never distorts or misrepresents what He says or does. Lying is against His nature.
Fully recognizing God’s identity as the source of truth can only produce unshakable hope in His promises. Because it’s not even a question of whether He will fulfill His promises or not; the instant He speaks, it is true, even if we don’t see it immediately. Throughout Christ’s time on earth as a man, He spoke, and reality rearranged itself to accommodate.
Biblical scholar Chad Bird puts this reality beautifully when he said:
"God cannot lie. When He says we are forgiven, it's true. The fact that we believe adds nothing to the forgiveness. A person might say they believe the sun is shining, but the sun doesn't shine or shine brighter with that admission of truth."
Everything God has said, has come to pass. Even in the midst of the trials of this world we have a hope that is unparalleled by any other. This hope is an anchor for our souls and it is guaranteed by both the promise made and the oath taken (Hebrews 6:19-20). In the midst of life we can rest securely knowing that our future is secured, our hope is sure, and that our God is faithful to His Word.
"God is not human, that he should lie, not a human being, that he should change his mind. Does he speak and then not act? Does he promise and not fulfill?" - Numbers 23:19