We are all self-indulgers. The whole lot of us. Let's just admit it upfront and help each other fight. Biblical self-indulgence is feeding the "passions of the flesh" (1 Peter 2:11). It's indulging ourselves in any pleasure that is harmful to our souls, that does not spring from faith (Romans 14:23).
Recognize the Danger
Self-indulgence is spiritually dangerous to us because it's a form of idolatry. It's something we turn to instead of God for happiness. It dulls our spiritual tastes and curbs our spiritual appetites (Proverbs 27:7). If we don't take it seriously, it can, like Solomon's wives (1 Kings 11:1–3), turn our hearts away from God.
Self-indulgence comes in all shapes and sizes. We can all name obvious or "gross" kinds (like those listed in 1 Corinthians 6:9–10). But perhaps for most of us the more dangerous indulgences are those that appear outwardly respectable. These are insidious because it is not the actions themselves that are sinful but our heart motives in doing them. So we may appear to do good while secretly indulging in pride (pursuing self-glory), greed or gluttony (too much of a good thing), negligence (should be doing something else), or lack of love (failing to serve someone else). This is what Jesus was talking about when he said:
"Woe to you, scribes and Pharisees, hypocrites! For you clean the outside of the cup and the plate, but inside they are full of greed and self-indulgence.: (Matthew 23:25)
Feel the Weight
But whether gross or "respectable," self-indulgence is a hard sin for us to fight because it's hard for us to want to fight it.
[Read the rest of the article at Desiring God.]