What does Matthew 6:21 mean?

A person's priorities are reflected by two sets of records: checkbooks and appointment books. In other words, where a person spends their money and their time is proof of what they truly value. Saying "this is important to me" is hypocrisy if not backed up with the way our lives are lived.

This well-known verse goes to the heart of Jesus' teaching in the Sermon on the Mount (Matthew 5:1–2). Most people in Jesus' audience grew up believing what mattered most to God was performance: action, behavior, and words. The Pharisees were thought to be the most spiritual because they closely followed behaviors tied to rules, regulations, and traditions. What Christ has been teaching is that God cares most about what His people are thinking and feeling. Righteous actions matter but are truly righteous only when accompanied by a devoted heart (Matthew 6:1–2, 5–6, 16–17).

Jesus has also applied this perspective to money. He has taught not to stockpile riches and possessions on earth. Those are temporary and easily lost. Instead, He has said, stockpile rewards in eternity by your true, inner devotion to God (Matthew 6:19–20). His point is not that Christians cannot have wealth, or they should not own anything. Rather, He means that we can only have one ultimate priority (Matthew 6:24), which should be God.

Attitudes toward wealth matter because our hearts are owned by whatever we consider our "treasure." That proves to be the real foundation of our thoughts, affection, and hopes. If we focus time, energy, and effort on building wealth for ourselves on earth, that wealth is what our hearts will focus on. If we focus on building rewards from God in heaven, our hearts will focus on the experience of enjoying that "treasure" forever. Rather than being motivated by temporary wealth, we'll emphasize honoring God and His will.