The difference between righteousness by works and righteousness by grace is illustrated by a ride on a commuter train.

A train rumbles into the station with warning bell clanging. The doors open, the uniformed conductor steps out, and you climb on board and find your way to a seat. When you look around the car, you see tickets clipped on the top of occupied seats, paid for with hard-earned money. Those tickets displayed at each seat are the special concern of the conductor, who walks through the car to punch tickets and confirm that you paid for the right to take this ride. If the conductor finds you without a ticket, you will either pay on the spot or be escorted off the train at the next stop. To ride this train, what matters is the paid ticket. This is righteousness by works.

Righteousness by grace, on the other hand, works in a very different way. God's train pulls into the station, warning bell clanging. The doors open and the conductor steps out. Masses of people crowd on board and find their seats, for most everyone wants to ride this train to the city where people never die. Eventually the conductor walks through the train to see if everyone belongs on board. But on this train the conductor is not looking for tickets clipped to the top of seats. In fact, anyone who tries to pay for the right to be on the train will be escorted promptly from the train at the very next stop. That's right; no one can earn the right to be on this train. What the conductor looks for as he walks seat by seat through the car is the penniless people he knows by name, the people who are his friends and who completely lack the means to pay. These poverty stricken people climb on board with only one hope: they believe in the generosity of their conductor friend.

This is righteousness by grace. A ride on God's train is a gift. By our standards, it's unfair. It's scandalous. But like it or not, it's heaven's way.