You must know truth from error 

“Here is another story Jesus told: ‘The kingdom of heaven is like a farmer who planted good seed in his field. But that night as the workers slept, his enemy came and planted weeds among the wheat, then slipped away. When the crop began to grow and produce grain, the weeds also grew. The farmer’s workers went to him and said, ‘Sir, the field where you planted that good seed is full of weeds!’…‘An enemy has done this!’ the farmer exclaimed. ‘Should we pull out the weeds?’ they asked. ‘No,’ he replied, ‘you’ll uproot the wheat if you do. Let both grow together until the harvest. Then I will tell the harvesters to sort out the weeds’” (vv. 24-30 NLT). There are two important lessons here. (1) You must know God’s Word so well that error, regardless of how convincingly it’s presented, can’t mislead you. Paul warned the leaders of the church at Ephesus: “Even from your own number men will arise and distort the truth in order to draw away disciples after them. So be on your guard!” (Acts 20:30-31 NIV). (2) You must stay spiritually awake and alert. Notice, the seeds that were sown that night didn’t produce a harvest of weeds until later. And at that point they could not be uprooted. Perhaps you think this is no big deal. Think again! One degree off course may seem harmless enough. But if you stay on that trajectory long enough, spiritually speaking, you will end up far from where God wants you to be and realize “an enemy has done this”! So what is the answer? “They devoted themselves to the apostles’ teaching…to fellowship…the breaking of bread and…prayer” (Acts 2:42 NIV).