"And now the second point; it is a yet more terrible one to dwell upon, and if I consulted my own feelings I should not mention it; but we should not consider our feelings in the work of the ministry, any more than we should if we were physicians of men's bodies. We must sometimes use the knife, where we feel that mortification would not ensue without it. We must frequently make sharp gashes into men's consciences, in the hope that the Holy Spirit will bring them to life. We assert, then, that there is a NECESSITY that God should whet his sword and punish men, if they will not turn. Earnest Baxter used to say, 'Sinner, turn or burn! It is thine only alternative. TURN OR BURN!' And so it is. We think we can show you why men must turn, or else they must burn." (Source Turn or Burn)
Recommended reading:
You can also listen to an audio recording of The Forgotten Spurgeon on Sermonaudio.com: