Agatha Christie and Christian despair

In her autobiography, Agatha Christie recalls a moment in a lesson when her teacher stopped speaking about maths and suddenly changed the subject:

"All of you,” she said, “every one of you—will pass through a time when you will face despair. If you never face despair, you will never have faced, or become, a Christian, or known a Christian life. To be a Christian you must face and accept the life that Christ faced and lived; you must enjoy things as he enjoyed things; be as happy as he was at the marriage at Cana, know the peace and happiness that it means to be at harmony with God and with God’s will. But you must also know, as he did, what it means to be alone in the Garden of Gethsemane, to feel that all your friends have forsaken you, that those you love and trust have turned away from you, and that God Himself has forsaken you. Hold on then to the belief that that is not the end. If you love, you will suffer, and if you do not love, you do not know the meaning of a Christian life... ” Years later [those words] were to come back to me and give me hope at a time when despair had me in its grip.