There are a lot of metals that on the surface look similar to gold. Centuries ago, people discovered that unscrupulous operators would take advantage of this to trick people into paying for worthless metal. In order to determine whether gold was genuine or not, scientists devised an “acid test.” The item that is supposed to be gold is rubbed on a black stone, leaving a mark behind. Gold is what is called a noble metal, meaning that it is resistant to the corrosive effects of acid. If the mark is washed away by the acid, then the metal is not real gold. If it remains unchanged, the genuine nature of the gold is proven.
It is not always immediately apparent from the outside whether someone is a genuine believer doing work for God out of good motives or not. Some are tares among the wheat while others are doing the right things but for selfish motives. It is only when faith and works are put to the test that it will become clear. Not all of these tests will turn out as people expect. Jesus said, “Many will say to me in that day, Lord, Lord, have we not prophesied in thy name? and in thy name have cast out devils? and in thy name done many wonderful works? And then will I profess unto them, I never knew you: depart from me, ye that work iniquity” (Matthew 7:22-23).
Those who are believers will stand at the Judgment Seat of Christ where their labor will be tested. Those who have put their trust in Christ can never lose the eternal life Christ promised, but our labor for the Lord will be tried. Paul wrote, “Every man's work shall be made manifest: for the day shall declare it, because it shall be revealed by fire; and the fire shall try every man's work of what sort it is” (1 Corinthians 3:13). Only that which has been done with pure motives and for the glory of God will survive that judgment.