Look: I, Paul, say to you that if you accept circumcision, Christ will be of no advantage to you.  I testify again to every man who accepts circumcision that he is obligated to keep the whole law.  You are severed from Christ, you who would be justified by the law; you have fallen away from grace.  For through the Spirit, by faith, we ourselves eagerly wait for the hope of righteousness.  For in Christ Jesus neither circumcision nor uncircumcision counts for anything, but only faith working through love.
Imagine that you are in a park on a nice sunny day and you decide to go up to a handful of strangers and you ask them this question, “What is your definition of a good person?” Can you even begin to imagine the answers you might get? A good person is someone who is kind to others. A good person pays their taxes. A good person doesn’t do harm to others.
Now those answers seem reasonable don’t they? But what about these: A good person always recycles and never drives an SUV. A good person would never be a republican. A good person would never have voted for Donald Trump. A good person would never have millions and millions of dollars, but instead would give it all way to the poor. How would you respond to those?
If you are a sane person, you would, on some level, be outraged that people held such ridiculous standards for what it means to be a good person.
But isn’t this exactly what we do in Christianity? Don’t we tend to setup arbitrary rules and standards for what it means to be a Christian? We tell people that a Christian doesn’t ever drink alcohol. If someone is a Christian they would never watch anything on secular television. If someone is a real Christian they will read their Bible and pray everyday (disclaimer: I think daily Bible reading and prayer are good things, but are not required to be a Christian). Someone might be so bold to say that if a person is not directly helping the poor or marginalized people groups they can’t be a true Christian. The list could go on and on.
But what did Paul say, “If you accept circumcision, Christ will be of no advantage to you.” Translation? If you base your Christianity on a man-made, arbitrary standard, other than trusting in Christ and his finished work on the cross than you are not a Christian. Why?
Because you have trusted in something else besides Jesus to save you and make you right with God. Salvation is by grace alone through faith alone in Christ alone.
Am I saying that works don’t matter? No! Good works that are consistent with scripture should be the fruit of our belief in Christ. But they can’t save you. Only Christ can.
So next time you feel tempted to define what a Christian is, be sure that you are defining it the way the Bible does. Don’t base it on your arbitrary standards and rules. Instead, look to the Bible, look to the standards it gives, and be sure that faith in Christ alone is at the very center of how you measure someone else’s Christianity.