# came down from Judea

The phrase "came down" is used here because Judea is higher in elevation than Antioch.

# taught the brothers

"taught the believers at Antioch" or "were teaching the believers at Antioch" 

# Unless you are circumcised according to the custom of Moses, you cannot be saved

"Unless someone circumcises you according to the custom of Moses, God cannot save you" or "God will not save you from your sins unless you receive circumcision according to the law of Moses"