The most useful life for God must ever be that which is firmly based on a knowledge of Christ crucified as the sole ground of acceptance with God, and on being justified and having peace "through our Lord Jesus Christ, who died for us." 1 Thess. 5:9, 109For God hath not appointed us to wrath, but to obtain salvation by our Lord Jesus Christ, 10Who died for us, that, whether we wake or sleep, we should live together with him. (1 Thessalonians 5:9‑10).
One who would serve God and his fellowmen acceptably must know himself to be forgiven by God and safe for eternity. It is written of Robert McCheyne, the Scotch preacher, that "he walked calmly in almost unbroken fellowship with the Father and the Son." McCheyne himself describes his own undoubted conversion in the only record he has left of it:
"When free grace awoke me, by light from on high,
Then legal fears shook me, I trembled to die;
No refuge, no safety in self could I see—
Jehovah Tsidkenu my Savior must be.
"My terrors all vanished before the sweet name,
My guilty fears Banished; with boldness I came
To drink at the Fountain, Life-giving and free—
Jehovah Tsidkenu is all things to me."