Why would God allow deception?

from the old testament

• The book of Numbers distinguishes God from man with the point that human beings lie, but God never does(Numbers 23:19).
• The ninth of the Ten Commandments forbids lying (Exodus 20:16).
• In rare circumstances, when faced with two evils in which lying is the lesser of the evils, the Bible suggests that lying is tolerated. For example, when the king of Egypt told the Hebrew midwives to kill all male children born to Hebrew women, they disobeyed that order to murder. When the king called them to account for that, they lied and told him that the births were happening before they were called to the homes. Immediately after that, Exodus 1:20 says, “So God dealt well with the midwives. And the people multiplied and grew very strong.” Their choice is understandable, but that doesn’t mean God approved of the lie; it means that He approved of them refusing to murder infants.

from the new testament

• "False prophets will rise up and perform great signs and wonders so as to deceive, if possible, even God’s chosen ones" (Matthew 24:24). Believers need to remain steadfast in their faith and grounded in Scripture.
• Satan is a liar, one whom Jesus called “the father of lies” (John 8:44). When we lie, we align ourselves with Satan.
• Do not be ensnared by empty deception that is hollow and lacks truth. Any teaching that detracts from the person and work of Jesus is to be rejected (Colossians 2:8).
• Deception can lead people away from the truth of the Gospel. Those who reject the truth of the Gospel, reject Jesus Christ and His salvation (2 Thessalonians 2:10-11).

implications for today

In today's society there is a great deal of deception and manipulation, from the political arena, to our schools, media, and even "Christian" churches. It’s our duty to be alert to deceptions so that we can oppose them.

This starts with knowing the truth so well that we recognize a lie when we hear it. We know the truth through studying God’s word.Jesus tells us to “beware of false prophets” (Matthew 7:15). Paul warned the Ephesian elders “from among your own selves will arise men speaking twisted things, to draw away the disciples after them” (Acts 20:30). In a letter to the Corinthians, Paul cautions believers to be alert to “false apostles, deceitful workmen, disguising themselves as apostles of Christ” (2 Corinthians 11:13); he links these to Satan who “disguises himself as an angel of light” (2 Corinthians 11:14). Deception is nothing new, and it hasn’t gone away. Jesus said, ‘You will recognize them by their fruits” (Matthew 7:16). Deceptive Christian cults that mislead people tend to be works oriented with unorthodox beliefs. Jehovah’s Witnesses deny the Trinity and the divinity of Christ, while Mormons believe in the existence of multiple gods and the potential for humans to become divine, none of which is biblical. The prosperity gospel of health, wealth and success is another false gospel that has taken root in many parts of the world. The prosperity gospel misrepresents biblical doctrine. The true Gospel emphasizes grace, sacrifice and eternal life over earthly prosperity.

Our role as Christians is to be prepared to resist such lies and to share the truth in love with others who are deceived (Ephesians 4:15).