Answer
Every human being is created in the image of God (Genesis 1:27; James 3:9). Part of what it means to be in God’s image is that we have a conscience that instinctively recognizes good and evil and tells right from wrong. Every civilized culture in the world has adopted similar standards for its people based on this inherent understanding of good and evil. Murder, theft, and deceit are universally understood to be wrong. Sometimes depravity overrides that knowledge, and a people group chooses to value evil rather than forbid it, as in the case of infanticide practiced by the heathen nations surrounding Israel (Leviticus 18:21; 2 Kings 23:10).
Due to our sin nature, we tend to excuse the evil in ourselves (Romans 5:12; Proverbs 20:20; Jeremiah 2:35). A continual pattern of excusing evil leads to a hardening of the conscience. Romans 1:28 gives God’s response to those who persist in evil: “Furthermore, just as they did not think it worthwhile to retain the knowledge of God, so God gave them over to a depraved mind, so that they do what ought not to be done.” There is a point at which God lets go. Those who insist on keeping their sin can now sin boldly and suffer no pangs of conscience. They believe they have transcended conscience and outsmarted God. But their judgment will come when they stand before Christ (Hebrews 9:27; Malachi 3:5).
As darkness is defined by the absence of light, sin is defined by the absence of goodness «Therefore to him that knoweth to do good, and doeth it not, to him it is sin.», (James 4:17). Since God embodies goodness (Psalm 86:5; Psalm 119:68), anything contrary to His nature is considered evil “for all have sinned, and come short of the glory of God;”, (Romans 3:23). We learn to differentiate between good and evil by understanding God. His Word serves as the basis for comprehending Him (Psalm 1:1-2; Psalm 119:160; John 17:17). The closer we draw to God’s holiness, the more apparent sin’s severity becomes “In the year that King Uzziah died, I also saw the Lord sitting upon a throne, high and lifted up, and His train filled the temple.”, (Isaiah 6:1,5) “Then I said, ‘Woe is me! For I am undone; because I am a man of unclean lips, and I dwell in the midst of a people of unclean lips: for my eyes have seen the King, the LORD of hosts.'”, (Isaiah 6:1,5). A t-shirt may appear white against a black wall. However, when placed on newly fallen snow, it looks quite dingy. Similarly, our attempts at goodness seem quite dingy when compared to God’s holiness. In His presence, we begin to recognize how self-centered our thoughts and actions are. We acknowledge our own greed, covetousness, lust, and deceit as the evils they are. It is only in God’s light that we truly see ourselves.
We also learn to differentiate between right and wrong by knowing the Word. After all, the Bible outlines what is sinful and what is not. The author of Hebrews discusses those who are spiritually immature, only able to handle spiritual “milk”—the fundamental principles of God’s Word “For everyone who uses milk is unskilled in the word of righteousness: for he is a babe.” (Hebrews 5:13). In contrast to the “babes” in Christ are the spiritually mature, “who by constant use have trained themselves to distinguish good from evil” “But strong meat belongs to them that are of full age, even those who by reason of use have their senses exercised to discern both good and evil.” (Hebrews 5:14). Note that a Christian’s spiritual senses are strengthened through the “constant use” of the Word. The ability to discern right from wrong, to distinguish between Christ’s doctrine and man’s, comes by studying and applying God’s Word.
God’s Word is filled with examples of those who did right and those who did wrong. Those examples are there for us to learn what God is like and what He desires from us “Now all these things happened unto them for examples: and they are written for our admonition, upon whom the ends of the world are come.” (1 Corinthians 10:11). Micah 6:8 gives a brief summary of God’s desire for every person: “He has shown you, O mortal, what is good. And what does the LORD require of you? To act justly and to love mercy and to walk humbly with your God.” Malachi 3:18 makes it even clearer. God says, “And you will again see the distinction between the righteous and the wicked, between those who serve God and those who do not.” Here the Lord is equating righteousness with serving Him. If good is defined as serving God, then evil is rejecting God and refusing to serve Him. Regardless of how philanthropic a person may appear to others, his good works amount to little if they are done for selfish reasons. If we make it our goal to seek God and honor Him in everything we do “Whether therefore ye eat, or drink, or wh…Whatsoever ye do, do all to the glory of God., (1 Corinthians 10:31). By seeking Jeremiah 29:13; 1 Peter 3:12; Psalm 106:3, we will comprehend right and wrong, ensuring that our life choices are pleasing to Him.