Today, many believers are throwing out the Old Testament, claiming its teaching is no longer relevant because of Christ's finished work on the cross. It's true that "the new covenant is established on better promises" (Heb. 8:6). But what exactly changed after the crucifixion and resurrection of Christ? Did God change? Is He a God of wrath or a God of mercy? The teaching of the Bible in its fullness—from Genesis to Revelation—provides the answer.

While we traditionally think of the Old Testament God as one of judgment and wrath, He is equally loving and tender. When we look at isolated events in Scripture, such as the flood or the annihilation of Sodom and Gomorrah, we may feel a sense of doubt about God's compassion. But what if He had allowed unbridled sin to grow? Could it be that these judgments were in reality acts of mercy—sparing the human race from itself? God's wrath is just, and His choice to patiently withhold it in its full measure throughout the Old Testament testifies to the depths of His merciful love. Conversely, those who see the New Testament as divulging only God's love and grace overlook God's wrathful acts and Jesus' harsh words and warnings in the New Testament (Acts 5:1-11, Matt. 11:20-24).

In reality, throughout Scripture, the all-wise God holds these two attributes—His wrath and His love—in perfect balance. In the Old Testament, God exerts fatherly patience and compassion toward mankind (Hos. 11:4, Jer. 31:3, Isa. 54:10). And in the New, He pours out His burning wrath toward sin on Jesus Christ to provide atonement for a wayward people—while also promising a Judgment Day to come when those who reject His gift of grace will be held accountable (Rev. 20:11-15).

God does not change. This simple Truth gives us hope that will last eternally, for it means we can know and trust God. His Word testifies to this Truth again and again. He is unchangeable in His person—in all His attributes: "I the Lord do not change. So you, the descendants of Jacob, are not destroyed" (Mal. 3:6). He is unchangeable in His plan for redemption: "Because God wanted to make the unchanging nature of his purpose very clear to the heirs of what was promised, he confirmed it with an oath" (Heb. 6:17). He is always faithful and loving, and what He promises perfectly comes to pass for His glory and the good of all creation. For in Him "there is no variation or shadow due to change" (Jas. 1:16, ESV; see also Num. 23:19; Ps. 102:24-27, 111:5-9; et al.). As preacher and author A. W. Tozer put it, "There will never be a change in God—no change is necessary!"

The New Testament completes the Old Testament as, in the fullness of time, according to His plan declared in the beginning (Gen. 3:15), God Himself becomes man, Jesus the Savior appears, and suddenly God, who lives in unapproachable light, is made approachable. But it isn't just His appearance in the flesh; it's the fact that through His blood shed on the cross, Jesus brings peace with God to everyone who calls on His name.

The Old Testament makes plain our need for salvation, for God provided the law to guide Israel in righteousness. But as Paul explains, the law was powerless to save us or take away our sins; we could never measure up on our own (Rom. 7:9-13). So, "what the law was powerless to do . . . God did by sending his own Son in the likeness of sinful flesh to be a sin offering" (Rom. 8:3). Jesus, the hope of all nations, fulfilled the covenant God made with Abraham to make him a great nation and to bless all nations through him (Gen. 12:3-4). Thus, the New Testament is the fulfillment of the old covenant and the establishment of a new covenant—God's promise to save those who trust in and follow His Son.

We must be wary of any attempt to pit the God of the New Testament against the God of the Old Testament, for there is but one God—the God of Abraham, Isaac, and Jacob. Knowing we serve the same God as Adam and Eve, Abraham, David, Peter, and Paul should cause overwhelming joy in our hearts. We can count on our Lord to always be Himself. When God told Moses in Exodus 3:14, "I ᴀᴍ ᴡʜᴏ I ᴀᴍ," He meant it. The Lord is telling you and me that His character doesn't change; He isn't moody, wishy-washy, capricious, or indecisive. He is just, loving, wise, present, slow to anger, merciful, gracious, and pure. His purposes are eternal and cannot be thwarted, and we can be confident His plans will never fail.

If we are to understand God's whole plan of redemption from Genesis to Revelation, we must seek to understand His whole character and submit ourselves to His whole counsel. If ever in doubt, we must turn to His Word—for as Deuteronomy 7:9 reminds us, "[T]he Lord your God is God; he is the faithful God, keeping his covenant of love to a thousand generations of those who love him and keep his commandments."