The church has spoken out very little and done virtually nothing in opposition to the presence and influence of gambling. Government, especially on the state level, is an advocate for gambling, and the church needs to take a stand, expose the evils of gambling, and declare how it's really at odds with the principles of Scripture.

Why gambling is wrong:

• Not justified by the casting of lots. In biblical times lots functioned much like dice. They were made of sheep's knuckle bones, and the roll of those bones indicated a certain meaning. When the people had to make an important decision and had difficulty determining God's will, He sovereignly intervened and caused the lots to fall in such a way as to tell His followers what to do. At no time did anyone ever put something of value at risk.
  
• Denies the reality of God's sovereignty. Chance, the major promise of gambling's outworking, is the fabric of a human imagination that wants to deny the existence of a sovereign God. The Lord has established His throne in the heavens, and His sovereignty rules over all (Ps. 103:19).
  
• Builds on irresponsible stewardship. The worst possible stewardship is for someone to throw God's resources away at the altar of a god called chance or luck. It's idolatry of the worst sort. Nothing we have really belongs to us; it belongs to God, and we should use all of it to His glory (Matt. 6:19-20).
  
• Erodes the biblical work ethic. We are to earn our bread by the sweat of our brows (Gen. 3:19) not from games of chance. The addictive wagering process saps the good that a decent salary can afford.
  
• Driven by the sin of covetousness. Gambling - and its accompanying greediness - violates the 10th commandment (Ex. 20:17). It assumes that God has not given us what we ought to have and that there is somehow more wealth that will finally make us happy.
  
• Builds on the exploitation of others. It exploits people who can least afford to be victims and violates the eighth commandment, You shall not steal (Ex. 20:15). For everyone who wins something at gambling, there are millions of losers - people who have been duped by the seductive marketing appeal of gambling and prompted to throw away large sums of money.
  

Answer taken from Beware the seductive fantasy of gambling by John MacArthur.  Click here to read the rest of the article.