When we contemplate these facts, the thought suggests itself that if we were just right, perfectly guided by the Spirit of truth, we should engage in no abortive labors; every stroke would tell for the kingdom of Christ; every word of exhortation or of instruction would accomplish its exact purpose, like the word of the Lord "which returneth not unto him void." We have recently heard persons testify to such a fullness and guidance of the Spirit that every effort to do good to others is successful, the Spirit directing, infallibly, to the susceptible persons, and suggesting the exact words needed for their deliverance.
But there must be some mistake in this matter. We find no instance of this in the Holy Scriptures. The holiest men are afflicted with a sense of failure in their labors. Sinners were hardened under the preaching of St. Paul. His failure to save his brethren of the Hebrew nation produced the profoundest sorrow, so that he could wish himself "accursed from Christ;" that is, that he could make an atonement in addition to Christ's, to secure their salvation. Jesus himself, when he gazed from Olivet upon the rebellious city soon to be desolated by the judgments of God, and cried "O Jerusalem, Jerusalem!" keenly felt the failure of his ministry. If we correctly interpret the language of God the Father, we must understand that even his absolute perfections do not exclude a painful sense of failure in his unsuccessful attempts to save free agents who pervert their godlike attribute of freedom by rejecting his mercy: "I have nourished and brought up children, and they have rebelled against me." He "willeth not the death of the wicked, but rather that they would turn and live: Turn ye, turn ye."
Therefore we do not teach the possibility of freedom from this sense of inefficiency in the present life. It is an element of our probation, one of the highest tests of faith, to toil for God when we see no fruit, to sow for others to reap, or for the birds to snatch away, or the thorns to choke. Was not this the bitter ingredient of that cup which made the Son of God a man of sorrows?
— edited from Love Enthroned, Chapter 6.