Commentaries:
He implies money, but the principle includes anything of such importance—apart from the Kingdom of God and His righteousness—that achieving it dominates our thinking, planning, and conduct. If it shapes our existence, we have a false god. The desire to "get" this thing replaces the devotion we should give to God and forces us into sins in other areas. Thus, we become idolaters.
John W. Ritenbaugh
The Second Commandment (1997)
Laying up—saving or storing—is not in itself sinful; Paul enjoins honest industry and wise enterprise (II Corinthians 12:14). If wealth comes our way, we should use it, not only for our ease and profit, but also for the good of others. Treasures on earth, if distributed for God's glory, become tools for laying up treasures in heaven.
It is natural for the human heart, mind, affection, and interest to be fixed on treasure. To regulate this fixation, it is important that the treasure be proper (Isaiah 55:2). We must be seeking the right goal—not physical riches but spiritually sound treasures in the form of deeds of kindness: good works (Luke 12:33) and the character formed by them (Revelation 14:13). Paul urges us to "be rich in good works" (I Timothy 6:18), partakers of "the unsearchable riches of Christ" and "the riches of His glory" (Ephesians 3:8, 16), and James advises us to be "rich in faith" (James 2:5).
The treasure of the converted is to be heirs of God and joint-heirs with Christ, to attain an incorruptible, undefiled inheritance that does not fade away. In the Kingdom of God, nothing corrupts, nothing dies away, and no enemies plunder or destroy (I Peter 1:4).
Martin G. Collins
Parable of the Treasure
Treasure is what we value highly, what we take great pains to serve, honor, preserve, and embellish.
John W. Ritenbaugh
Eating: How Good It Is! (Part Two)
By paying to God what we owe Him (that is, His tithes), He rewards us with blessings. Christians often find their third tithe years to be abundant with all types of blessings and invaluable lessons learned. These are not always material blessings, however. Storing up spiritual treasures in heaven is far more important than physical prosperity. God does not promise to make us wealthy but that our relationship with Him will prosper. Such eternal blessings are far greater than any temporary physical blessings we could receive.
Martin G. Collins
Tithing: Third Tithe
Other Forerunner Commentary entries containing Matthew 6:21:
Genesis 25:29-34
Exodus 32:1-6
Matthew 10:39
Luke 14:18