The U.S. Secret Service says the best way to detect counterfeit money is to become familiar with real money, looking for differences, not similarities.
They recommend you:
1. Look at the portrait because it should appear "lifelike" and stand out from the background.
2. Look at the treasury seal, borders and numbers which should appear distinct, not blurry.
3. Look at the paper which will have fibers "embedded," not simply printed on the surface.
This is also true when detecting counterfeit philosophies:
1. Look for God's "portrait." Is the truth God-centered or self-centered?
1 Corinthians 6:6-16
2. Look at the details of the philosophy. Is it clearly Scriptural or does it blur the lines between truth and error?
3. Look for the quality of the philosophy. Is God's truth embedded in it or is it simply a worldly philosophy with spiritual words on the surface? Colossians 2:8