If you’ve never heard of the term a_ fortiori_, you’ve almost certainly reasoned in a way that reflects its meaning. The idea behind it is basically this: “How much more then?” You draw an inference from a lesser point to a greater point.
Here’s an example. Suppose a child is able to lift a suit case. Now if the child can lift the suit case, how much more the kid’s father who is a bodybuilder?
Today, while reading the Word during my lunch break, I found myself in the fifth chapter of Romans. There, nestled in the opening verses, Paul utilizes the a fortiori argument. It’s elegantly simple with profound and glorious implications.
Here’s what he writes,
For one will scarcely die for a righteous person--though perhaps for a good person one would dare even to die-- but God shows his love for us in that while we were still sinners, Christ died for us. Since, therefore, we have now been justified by his blood, much more shall we be saved by him from the wrath of God. For if while we were enemies we were reconciled to God by the death of his Son, much more, now that we are reconciled, shall we be saved by his life. (Rom 5:7-10)
Paul begins by making a point everyone can appreciate: People just don’t throw down their lives for any ol’ person. Maybe for a good person, but even that’s rare.
Building on this Paul highlights the incredible depths of God’s love. Christ died for the ungodly. He died for people who were anything but good. And it was love that propelled Him to do this.
Now hit the pause button. Let’s think.
Were we enemies of God before we came to faith? Yes. Was our relationship with God good? Not at all. There was nothing within us that could commend us to God. And, quite frankly, we were alright with that. Sinners don’t really give a rip. And yet, while we were going our own way, silently (or flamboyantly) raising our fists against the King, God chose to do something that would perfectly mend the severed relationship. He made the first (and decisive) move by sending Christ to do the unimaginable.
With this in mind, consider the logic of Paul’s thinking. If when we were sinners (or enemies), God acted in such a way so as to bridge the seemingly unbridgeable, how much more, now that we’re actually forgiven and adopted into His family (one of His children!), will God preserve us and act in such a way so as to keep us from experiencing His wrath?
Think of it this way. When we were enemies, what did we do to merit God’s favor? Absolutely nothing. God acted unilaterally on our behalf. So now that we’re children and dearly loved as one of His sheep, being found righteous in His Son, shall we now slip into condemnation? Absolutely not! The force of the argument demands this answer.
God accomplished what you needed while a rebel, and God will accomplish what you need while a redeemed rebel. It’s an A Fortiori argument, and it’s magnificently glorious.
 In my mind, this is one of the premier passages establishing the doctrine known as the perseverance of the saints. The “much more” component, when coupled with Paul’s initial example, namely, the fact that God sent His Son to die for rebels, leaves little wiggle room for doubt. In fact, I would say that it leaves no doubt as to God’s effectual plan to keep each and every one of His sheep.