An alchemist once went to Leo X and declared that he had discovered how to change ordinary metals into gold. He expected to receive a huge sum of money, preferably in gold, for his discovery. Leo was very clever in responding to this announcement, though. He merely gave the alchemist a large purse in which he told him to keep the gold he would make from other metals.
God's way of working with mankind is very similar to what Leo did with this alchemist. In several places in Paul's writings he uses the phrase "the righteousness of God." The phrase often means "righteousness" which has its origin in God. This is in contrast to man's righteousness which we seek to develop within ourselves. Paul explains: "For, being ignorant of the righteousness that comes from God, and seeking to establish their own, they have not submitted to God's righteousness" (Rom. 10:3). If we appear before God and announce that we can change ordinary human thoughts and deeds into righteousness, God's response will be similar to that of Leo to the alchemist. Instead of rewarding us for our supposed discovery, he will give us the opportunity to stockpile our human righteousness. Our personal storehouse of righteousness will be as empty of merit as the alchemist's purse was of gold.
Instead of achieving righteousness on our own--something impossible for us to do due to the universality of sin--we should lay hold of God's righteousness through faith. Paul said he wanted to "be found in Christ, not having a righteousness of my own that comes from the law, but that which is through faith in Christ--the righteousness that comes from God and is by faith" (Phil. 3:9). As the great hymn "Rock of Ages" by A. M. Toplady puts it:
Not the labor of my hands
Can fulfill the law's demands;
Could my zeal no respite know,
Could my tears forever flow,
All for sin could not atone,
Thou must save and Thou alone.