If you don't know the Word of God then you have no plumb-line to compare words and actions to. Instead they fall prey to the deception of Satan our adversary. For example, even the unbelievers know and quote Matthew 7:1 where Jesus said, "Judge not, that you may not be judged." But here is the problem. Ignorance!
You see if you read the scripture you'd see that Jesus was in the middle of a sermon. What preceded Matthew 7:1 was chapter 6 where in Jesus taught us not to pray as the hypocrites in verse 5 and not to fast like the hypocrites in verse 16. When he got to 7:1 His audience understood it was implied that we were not to judge as the hypocrites did. This is clarified in verse 5 which no one every quotes Jesus when He says, "Hypocrite! First remove the plank from your own eye and then you will see clearly to remove the speck from your brother's eye."
Why in Matthew 7:15 - 20 He teaches us how to judge or discern a false prophet by examining their actions and comparing it to God's word. A tweet by Charlie Kirk on Twitter this morning about Adam Schiff provides a perfect example.