How to Mortify Sin

‘Be killing sin or sin will be killing you’, said John Owen. And so, Johann Gerhard (the great 17th Century Lutheran theologian) said, ‘that’s why it is of the utmost necessity that we diligently take note of how we are to daily exercise ourselves in the crucifixion of the flesh and the renewing of the Spirit.’ But how? Here are Gerhard’s answers. 

1. We mortify sin ‘through diligent, devout hearing, reading, and contemplation of the divine Word.’

Firstly, the Holy Spirit works through the Word. Through God’s powerful words of law and gospel in Scripture ‘the Holy Spirit will be efficacious in us so that we do not consent to the lusts of the flesh.’ The Lord sanctifies His people by His Word. ‘Love knowledge of the Scriptures and you will not love vices of the flesh.’

Secondly, the Word strengthens us as the food of our souls. Therefore, the Word ‘gives our inward man strength and power so that he can subdue and overcome the outward, old man.’

Thirdly, the Word of God is our teacher and trainer, our sword and fire for the fight. By it we may chop off, destroy, and burn ‘the evil lusts of the flesh when they try to sprout up within us.’ The Word directs us in our fight against indwelling sin. Gerhard tells us that, when we’re tempted by any sin, we should ‘immediately seize for yourself a little verse from God’s Word that will guard you against it’, for there is no sin ‘that can be named but that there is a special verse in Divine Scripture to counter it. So, for example, if you’re tempted to wrath and rage, meditate on Eph. 4:26, or, if by greed, wrap yourself in Mt. 16:26.

2. We mortify sin ‘through the prompt suppression of the very first sinful movement.’

Don’t give temptation and sin the opportunity to get comfortable in your heart. ‘When an evil lust rises up in the heart, a person should not hang on to it in order to inflame oneself with lust, carry a desire for it, continually stir it up and think about it. Instead one should immediately throw it out and direct the thoughts of one’s heart to something else.

Gerhard recognises that reality and power of temptation:

‘Of course, we cannot prevent a sinful desire to arise in our heart like a flame that flares up. However, at the same time, we can guard ourselves that we do not bear a love and affection for it and cling to it.’

Cling to Christ, not to sinful desires.

3. We mortify sin ‘through the shunning and turning away from the opportunity to sin.’

There are precautions to be taken in avoiding falling into sin. ‘Whoever wants to protect himself from sinning must on all accounts shun the opening and opportunity to do so. Whoever does not want to get burned must not get too close to the fire.’

4. We mortify sin ‘through believing, earnest prayer.’

The mortification of sin is not something we can accomplish by and for ourselves. This is God’s work in us by the Spirit. And so, ‘since the crucifixion and subjugation of the flesh with its lusts requires the special power of the Spirit, it is essential that we obtain the same through a believing, earnest prayer, a longing sigh.’

(All the quotes from Gerhard are taken from his Schola Pietatis, Vol. 2.2, chapter 12)