“A Reformed Christian must naturally be Reformed in his approach to the problem of apologetics. Men and women do not walk about first as human beings and afterward as men and women. No more can a Reformed Christian first appear as a Christian and later as a Reformed Christian. A Reformed Christian is a Reformed Christian from the outset…
“…Would you first convert [an unbeliever] to evangelicalism and then to the Reformed Faith? Then you would be like a dentist who would today take half the decayed matter out and fill the cavity, and tomorrow or next week take out the rest of the decayed matter and fill the cavity again. Or, rather, you would be like the dentist who takes part of the decayed matter out, fills the cavity, and then lets the patient go until a long time later he returns complaining again of a toothache.
“Indeed, it is no fun to have the dentist drill deep into your tooth. And it is the last and deepest drilling that hurts most. So [the unbeliever] is likely to feel more at home in the office of the ‘evangelical’ dentist than in the office of the ‘Reformed’ dentist. Will the latter have any customers? He is likely to fear that he will not. He is ever tempted, therefore, to advertise that he is cooperating with all good ‘conservatives’ in all good dentistry, but that he has a specialty which it would be very nice for people to see him about.”
-Cornelius Van Til in The Defense of the Faith (1955), p. 306, 312-313