XXV. They Who Fear and Will Not Believe.
How long, O foolish man, will you not acknowledge Christ? You avoid the fertile field, and castest your seeds on the sterile one. You seek to abide in the wood where the thief is delaying. You say, I also am of God; and you wander out of doors. Now at length, after so many invitations, enter within the palace. Now is the harvest ripe, and the time so many times prepared. Lo, now reap! What! Do you not repent? Thence now, if you have not, gather the seasonable wines. The time of believing to life is present in the time of death.
The first law of God is the foundation of the subsequent law. You, indeed, it assigned to believe in the second law. Nor are threats from Himself, but from it, powerful over you. Now astounded, swear that you will believe in Christ; for the Old Testament proclaims concerning Him. For it is needful only to believe in Him who was dead, to be able to rise again to live for all time. Therefore, if you are one who disbelievest that these things shall be, at length he shall be overcome in his guilt in the second death. I will declare things to come in few words in this little treatise. In it can be known when hope must be preferred. Still I exhort you as quickly as possible to believe in Christ.
Source: Writings (New Advent)