The Bible defines sin as the transgression of God's spiritual law, the Ten Commandments (I John 3:4). One of these commandments is that we must not covet, or wrongfully desire another's possessions (Exodus 20:17). Therefore, any activity that is based upon covetousness is sin.
Jesus explains that the second greatest commandment is that we are to love our neighbor as ourself (Matthew 22:39). This cannot be done when we are competing in a coveting attitude for another man's things, as in a bet. A Christian should not desire to increase his own wealth by depriving someone else. When the attitude of greed is present, the activity is wrong regardless of the value of the wager. The Bible says that those who have this attitude will not inherit the Kingdom of God (I Corinthians 6:10; Ephesians 5:3-5), and I Timothy 6:9-10 warns against falling into the trap of lusting after riches.
The apostle Paul mentions another principle that applies to gambling: the work ethic. He writes, "If anyone will not work, neither shall he eat" (II Thessalonians 3:10). Gambling is often seen as a way to get something for nothing or without working for it. The Bible frequently warns against laziness, indolence, and sloth (see, e.g., Proverbs 6:6-11; 18:9; 19:15; 20:4; 21:25-26; 24:30-34; 26:13-16; etc.) because God Himself is a planning, creating, working Being who puts His all into everything He does and expects the same from us (Ecclesiastes 9:10). Gambling is often the lazy person's solution of getting out of work or debt or "striking it rich quick." The fruit of such schemes—neglect of family, poverty, divorce, theft, etc.—show they should be avoided (Matthew 7:16; Galatians 6:7-8).
Cards, dice, games of chance, and the like, are not inherently wrong. God's church has long understood that it is not the thing that is wrong, but the wrong use of the thing that results in sin. For example, a card or bingo game played for fun is not wrong even if poker chips, peanuts, or other items are used. In such cases, coveting is not involved. Thus, every such activity should be viewed from the standpoint of this principle: When an activity causes us to break one of God's Ten Commandments, it is a sin.
It is, of course, not our intent to try to spell out or address every possible kind of activity which may involve putting up something of value for the chance of winning a reward. We should simply keep in mind the scriptural principles mentioned previously when making our decisions.
God holds each of us responsible for how we live. If we are truly yielded to Him and are seeking His Kingdom and righteousness first as Jesus instructs (Matthew 6:33), God will give us the wisdom to make the correct choices in our lives.