“…wage the good warfare, holding faith and a good conscience. By rejecting this, some have made shipwreck of their faith…” 1 Timothy 1:18b-19
Paul gives two combats tips concerning waging the good warfare; a weapon for each hand. You fight the good fight of the faith by holding faith, and holding a good conscience. The first tip makes perfect sense, as much as the drill sergeant yelling, “You kill the enemy by shooting him!” But the second tip sounds like, “You kill the enemy with good hygiene.” Huh? Yet, it’s as simple as this, when trench foot impairs, disables, or kills you, it hurts the campaign. Shoot the wolves, and stay healthy—that’s how we win.
“This,” in v. 19 is singular. It is by rejecting a good conscience particularly that some have made shipwreck of the faith. Holding a good conscience is waging the good warfare. We must contend for the faith lest we be a heretic.
There are two routes to heresy, the interstate and the backroads. The interstate is clearly marked with big green signs that read, “PELAGIANISM—NEXT RIGHT,” or “MODALISM—THREE MILES.” You know where you’re going and you mean to go there. Then there are the backroads of immorality. You were on the well-lit heavenly highway but you messed up. You pulled off the road because you wanted some darkness. Now your lost and scared, but you like this darkness, so you delude yourself. You redraw the map. You convince yourself that if you just keep this direction, you’ll still get to the heavenly city.
John Calvin wrote, “All the errors that have existed in the Christian Church from the beginning, proceeded from this source, that in some persons, ambition, and in others, covetousness, extinguished the true fear of God. A bad conscience is, therefore, the mother of all heresies.” Really? But listen to how well Calvin’s assessment jibes with Scripture.
“If anyone teaches a different doctrine and does not agree with the sound words of our Lord Jesus Christ and the teaching that accords with godliness, he is puffed up with conceit [Do you hear ambition?] and understands nothing. He has an unhealthy craving for controversy and for quarrels about words, which produce envy, dissension, slander, evil suspicions, and constant friction among people who are depraved in mind and deprived of the truth, imagining that godliness is a means of gain [See covetousness?].” —1 Timothy 6:3–6
Still not convinced?
“But false prophets also arose among the people, just as there will be false teachers among you, who will secretly bring in destructive heresies, even denying the Master who bought them, bringing upon themselves swift destruction. And many will follow their sensuality, and because of them the way of truth will be blasphemed. And in their greed they will exploit you with false words. Their condemnation from long ago is not idle, and their destruction is not asleep.”
Just as sound belief and sound behavior go together, so do heresy and immorality (1 Timothy 1:5–6, 10; 6:3). And the relation is mutual. Heresy not only leads to immorality. Immorality leads to heresy.
“Doctrinal purity must be accompanied by purity of life. There is an inseparable link between truth and morality, between right belief and right behavior. Consequently, theological error has its roots in moral rather than intellectual soil (cf. Matt. 7:15-20). People often teach wrong doctrine to accommodate their sin. That truth is borne out by the immorality that so often characterizes false teachers.” —John MacArthur