Don’t judge, or you will be judged. The judgements you make you will be made against you, and the measures you take will be taken against you.
Many have thought this statement to imply that if you judge others here in the world, you will be judged in Heaven. But why then will the very judgements you make against others be made of you? I believe what Jesus is saying here is simply that people project their own faults onto others. He follows this up by pointing out that we tend to see the smallest fault in others, but are blind to our own:
Why do you the spec in your brother’s eye, but not the beam that is in your own eye? How can you say to your brother, “Let me take the spec out of your eye” when there is a beam in your own eye? You hypocrite! First cast the beam out of your own eye. Only then you will see clearly enough to take the spec out of your brother’s eye.