May a Christian woman wear makeup?

Yes, a Christian woman may help her face, if she does it modestly and emphasizes character and conduct over appearance (I Tim 2:9-10; I Pet 3:3-4). The fact that Peter condemned putting on of apparel indicates he taught about emphasis and priority, for women should always be clothed in public. God is against women that emphasize looks over spirits (Is 3:16-24; II Kgs 9:30).