ANSWER: Let us first begin with a definition before we tackle the issue of sin. What we commonly refer to as makeup are various substances and chemical compounds people wear for the express purpose of enhancing their appearance. In modern times, the use of cosmetics is not limited to females, or to being applied only to the face (non-facial scars or birthmarks are sometimes covered), or used only by adults (teenagers sometimes use them to cover the effects of acne).
Without a doubt, makeup has been a hotly debated, and many times divisive, topic among churches and fellowships. Some women have even been ejected from church services (and told never to come back) because they dared to wear cosmetics. Discussions centering on whether such practices, not clearly delineated in Scripture, are acceptable or not (a sin) have raged for quite a while.
"During the past several generations some of the strongest debate among fundamentalists and evangelicals (regarding sin) has centered around questionable practices . . . Some of the key issues have been drinking alcoholic beverages, smoking, card playing, wearing makeup . . ." (MacArthur New Testament Commentary on 1Corinthians).
It should be noted that English words such as "makeup" or "lipstick" are not found in Scripture. Direct references to the use of cosmetics are somewhat rare in the Old Testament, occurring only four times (2Kings 9:30, Isaiah 3:14 - 16, Jeremiah 4:30 and Ezekiel 23:40). The first Biblical reference involves former Israelite Queen Jezebel "painting her face" (applying makeup) in order to try to win the favor of Jehu, the newly anointed king of Israel (2Kings 9:1 - 6, 30). Her attempt to win favor, however, failed miserably (verses 32 - 37).
A basic principle
We need look no further than the creation of man for a guiding principle regarding whether or not it is a sin to wear makeup.
The Bible states that God made everything, including humans and the Garden of Eden, "exceedingly good" (Genesis 1:31, HBFV throughout). He filled the garden with an incredible variety of plants and trees, and even created a way for the area to be constantly watered (Genesis 2:6, 9 - 10). He then placed Adam (and soon Eve) in the garden with the express purpose that they "dress it and keep it" (verse 15). What did he, however, expect them to do since everything around them was unspoiled and did not so much as contain a single weed (weeds would grow AFTER sin entered the picture, see Genesis 3:17 - 18)?
God's will was that the first man and woman use their creativity to change and build upon what they were given. Rather than commanding they leave everything untouched (since it was already "good"), he expected and desired that they alter (guided by righteousness and wisdom) the garden to expand and further beautify it as they saw fit. Enhancing what the Eternal made was not wrong. Based upon this principle, it is not a sin if a woman uses makeup to enhance her appearance and the natural beauty she has received.
New Testament admonitions
What we find in the New Testament is NOT a condemnation of makeup as a sin but rather admonitions regarding its proper place and priority in a person's life. The Apostle Paul encourages Christian women to dress modestly and not draw unnecessary attention to themselves by how they look. Though cosmetics are not forbidden, emphasis should be placed far more on doing good than looking good (1Timothy 2:9 - 10). Peter also admonishes females (especially those married) to place their primary focus not upon how they look but rather on manifesting a righteous character (1Peter 3:3 - 4).
Wearing makeup (like drinking alcohol) is a question of moderation rather than prohibition. While it is certainly not wrong to forego cosmetics, using them with wisdom and modesty is not a sin. It would be wrong, however, to use them for the express purpose of leading another person to lust and disobey God in their heart. Believers should always be mindful how what they say, and do, will be perceived by others (1Thessalonians 5:22 - 23).
Job, after enduring the testing of his faith, was blessed with seven sons and three daughters (Job 42:13). His third daughter he named Keren-happuch (verse 14), a name that means "horn of cosmetic" (Strong's Concordance #H7163) or "horn of antimony" (Brown-Driver-Briggs Hebrew Definitions). Anciently, rocks composed of antimony were ground into a powder and used as eye makeup. The use of such enhancements, which was not a sin, no doubt played a part in the Bible declaring, ". . . in all the land there were not found women as beautiful as the daughters of Job" (Job 42:15).
According to MacArthur's New Testament Commentary, some first century Jews resorted to unique measures to advertise they were fasting. They would sometimes wear old or tattered clothes, or cover themselves in ashes, in order to promote their piety while they fasted. Makeup was even used by some in order to make themselves look pale so that they could effectively advertise how "righteous" they were! Jesus warned believers not to do such things (Matthew 6:16 - 18).