Whats not true???
Your statement.
Because the Word of God teaches that all true believers in Jesus Christ will GIVE EVIDENCE that they are His. As soon as a person puts His trust in Christ He is born again—the old man (the old self, all that we were in Adam) dies—he is identified with Christ and His death, burial, and resurrection; he is a “new creation,” and the old man has been crucified with Him, that our body of sin might be done away with, that we should no longer be slaves to sin Romans 6, and he has been raised up with Him to walk (live) in newness of life.
The N.T. is full of many Scriptures that clearly say that the new man has a new life in Christ, with a different walk (walk = way of living). The walk is EVIDENCE of the believer’s relationship with the Father through His Son, the Lord Jesus Christ.
So, how to explain your “experiences” as a waiter, etc.?
You “see” and immediately judge that these people you see (my, my, why are you looking, it’s supposed to be between them and God) are Christians who somehow “cheat” the people who wait on them, but you yourself are so great, you double tip them.
Well, #1, they may or may not be Christians. You are, afer all, just looking at an incident per person, not a lifestyle (walk) of a person. #2, you don’t know if they are a true Christian or not. In fact, you don’t know anything about the person being waited upon, or the server.