God’s unchanging faithfulness is beyond our limited human comprehension. His faithfulness is essential … without it he would not be God. Arthur Pink said, “For God to be unfaithful would be to act contrary to his nature, which is impossible.”  

If we are faithless, he remains faithful—for he cannot deny himself.—2 Timothy 2:13

... who is mighty as you are, O Lord, with your faithfulness all around you?—Psalm 89:8

Righteousness shall be the belt of his waist, and faithfulness the belt of his loins.—Isaiah 11:5

Your steadfast love, O Lord, extends to the heavens, your faithfulness to the clouds.—Psalm 36:5

Like everything else about God, his faithfulness is great, vast, incomparable. He never forgets, never fails, never stumbles, never goes back on his word. He always keeps his promises.

God is not man, that he should lie,
or a son of man, that he should change his mind.
Has he said, and will he not do it?
Or has he spoken, and will he not fulfill it?—Numbers 23:19 

God’s faithfulness is not just for our head knowledge. It is not just good theology. What we know about God’s faithfulness is encouraging food for our soul. What we learn about our faithful God becomes for us a sword, a shield, a rock of refuge. God’s faithfulness motivates us and causes hope to rise. We rest confidently on his strong unwavering arms. 

A.W. Tozer wrote, “Upon God’s faithfulness rests our whole hope of future blessedness. Only as he is faithful will his covenants stand and his promises be honored. Only as we have complete assurance that he is faithful may we live in peace and look forward with assurance to the life to come. Every heart can make its own application of this truth. The tempted, the anxious, the fearful, the discouraged may all find new hope and good cheer in the knowledge that our Heavenly Father is faithful. He will always be true to his pledged word. The hard-pressed sons of the covenant may be sure that he will never remove his loving-kindness from them nor allow his faithfulness to fail.”

When we look to the past, we may have regrets and sorrows or may be tempted with longings for “the good ol’ days.” When we look to the future, we can be filled with happy anticipation or with feelings of anxiety. Joshua, Moses’ assistant, knew what this was like when Moses died. He looked to the past and saw his former “boss”... the great law-giver, the competent administrator, the all-but-invincible leader of God’s people who led them through the sea on dry ground and provided fresh water by striking a rock. How could Joshua possibly fill those sandals? He looked to the future and saw a hot, dusty desert and a stubborn, leaderless people who were grumbling, complaining, and surrounded by their enemies. Would God continue to be faithful? Could he trust God?

Then God showed up and told him, “Every place that the sole of your foot will tread upon I have given to you, just as I promised to Moses” (Joshua 1:3). Do you notice the tenses of the verbs God used? Again in verse 5, God linked the past and the future with a promise, “Just as I was with Moses, so I will be with you. I will not leave you or forsake you.” God, the great I AM, always faithful, ties the past and the future together. As he was faithful to Moses in the past, so He would be faithful to Joshua in the future.

Because of God’s unchanging faithfulness, I hear him say to me, “As I was with Joshua, so I will be with you.” The past has its joys and pains, its health and sickness, its wins and losses, its success and adversity. Yet we can say,

Through many dangers, toils and snares, I have already come;

’Tis grace hath brought me safe thus far, And grace will lead me home.

We do not and can not know what the future holds. Yet God says not only “I was” …. but with all authority, “I AM and I will be.” His faithfulness links the past, present, and future. God is always faithful.

God’s faithfulness is not dependent on our faithfulness to him. God is continually faithful, no matter what we do. This gives us reason for complete confidence in him. Despite our raw emotions and regardless of our surrounding circumstances, our trust can rest in the fact that God is always faithful. If that is true, what can shake us? We can trust God and rest in peace and security. 

The steadfast love of the Lord never ceases; his mercies never come to an end; they are new every morning; great is your faithfulness.—Lamentations 3:22–23