Read the first verse (you know it well):

Judge not, that ye be not judged.

Matthew 7:1

Now read the rest of it (A.K.A. “that part we don’t read”):

For with what judgment ye judge, ye shall be judged: and with what measure ye mete, it shall be measured to you again.
And why beholdest thou the mote that is in thy brother’s eye, but considerest not the beam that is in thine own eye?
Or how wilt thou say to thy brother, Let me pull out the mote out of thine eye; and, behold, a beam is in thine own eye?
Thou hypocrite, first cast out the beam out of thine own eye; and then shalt thou see clearly to cast out the mote out of thy brother’s eye.

Matthew 7:2-5

It’s sometimes said “Oh I’m supposed to judge people…I’m supposed to judge; it’s how I know who is good and who is bad.”

My face when I hear that

JESUS SAYS YOU’RE NOT SUPPOSED TO JUDGE PEOPLE!  STOP JUDGING PEOPLE!

Stop looking at someone and assuming they are wrong. Stop finding little flaws and making them huge (mountains out of mole hills, as the saying goes).

I get what people mean when they say that, though. Here’s the verse they’re looking for:

Judge not according to the appearance, but judge righteous judgment.

John 7:24

But let’s understand what Jesus means here: If I’m not supposed to judge by appearance, what am I to judge? Listen, “don’t judge” in v1 means “don’t PREJUDGE!” Don’t be prejudicial, in other words. But someone says “well you don’t judge by appearance (Jesus says that) so you judge by action.”

No. Hold on: Let’s say someone acts like a jerk to me at the supermarket, am I to conclude “that guy ACTED mean, therefore he IS mean”? Absolutely not! The guy may not be mean at all. He might just be having a bad day and he might have just lost his temper. That’s wrong, yes, but that doesn’t mean he’s a bad person. He’s no worse than you are when YOU lose your temper. THAT’S what Jesus means when he says don’t judge. When you jump to a conclusion and make assumptions about people you are prejudging them, based on very little evidence. And along the way you forget that you need the Grace of Jesus just as much as the next guy. “Judging” doesn’t mean telling a sinner to repent (we’re supposed to do that). It means “don’t (pre)assume someone is a sinner without reason.”

Don’t do that.

Don’t.