(Scripture quotations are from the New International Version Bible, unless otherwise noted.)
Obedience to God brings life and blessings; disobedience brings death and misery. When Adam disobeyed God and ate of the tree of knowledge of good and evil, he and all his future children were sentenced to death. (Genesis 2:17) Obedient Abraham was blessed with "the gospel" (Galatians 3:8): "Through your offspring all nations on earth will be blessed, because you have obeyed me," Genesis 22:18. Later, God gave Israel the law covenant, and gave them a choice. "See, I set before you today life and prosperity (through obedience), death and destruction (through disobedience)…Now choose life that you and your children may live," Deuteronomy 30:15-19.
As we know, Israel could not keep the law, therefore God provided the gift of His Son as "the atoning sacrifice for our sins, and not only for ours but also for the sins of the whole world," 1John 2:2; 4:10. Some believers might think that obedience is no longer important. But the Apostle Paul clarifies this point: "Shall we go on sinning so that grace may increase? By no means! We died to sin," Romans 6:1-3.
At this time, God is calling people who are willing to "take up [their] cross" to follow His Son, Jesus (Matthew 10:39; 16:24). A true Christian's walk includes opposing the world, our fallen flesh, and the devil. Obedience is hard. But we are given promises to encourage us. 2 Timothy 2:12 (KJV), "If we suffer, we shall also reign with him: if we deny him, he also will deny us."
Jesus himself was perfected through obedience: He "learned obedience from what he suffered and, once made perfect, he…was designated by God to be high priest," (Hebrew 5:8-10). As Jesus had to prove His loyalty under adversity, the followers of Jesus have to be tested as well. And as Jesus was rewarded for His complete faithfulness to His Heavenly Father (Philippians 2:9), His followers are also promised a share in those rewards. 1 John 3:2 (ESV), "Beloved, we are God’s children now, and what we will be has not yet appeared; but we know that when he appears, we shall be like him, because we shall see him as he is."
In Christ's kingdom, all mankind shall come to know God, "for the earth will be full of the knowledge of the LORD," (Isaiah 11:9). Mankind's reward for obedience will be everlasting, perfect human life; peace and fellowship with God and man; and countless blessings. (Revelation 21:4, Isaiah 65:17-25)