So then it is not of him that willeth, nor of him that runneth, but of God that sheweth mercy. – Romans 9:16

However intent you may be in winning souls to Christ, you shall never meet with one who can be subdued to Him by any persuasions of yours apart from the working of His own power. I know the preacher has thought within himself, “I have only to put the truth in a reasonable way, and the man will see it.” Ah! sir, but sinners are not reasonable: they are the most unreasonable of all creatures: none are so senseless, none act so madly as they do. “But,” saith one, “if I were to tell them of the love of Christ in an affectionate loving way, that would reach them.” Yes, but you will find that all your affection and your tears, and earnest delineation of the love of Jesus, will be powerless against human hearts, unless the Eternal Spirit shall drive home your appeals. We know some who have been reasoned with, and if logic could win them, they ought to have been won long ago: they have also been persuaded, and if rhetoric could reach them, they ought to have turned away from their evil ways years ago; but all human art has been tried and tried, and tried in vain; yet there is no room for despair, for Jesus can conquer the unconquerables, and heal the incurables. Do not be disappointed, dear brother, if you have hitherto failed in your efforts; you have but proved that “vain is the help of man.” You see now by experience that “it is not of him that willeth, nor of him that runneth, but of God that showeth mercy.” It is yours to try and bring that soul to Jesus; but it lies with Him to perform the work. Duty is ours, the result is God’s. If the soil of the field committed to me will never yield a harvest, I am yet bound to plough it, if my Lord commands. If I could foresee that my child would never turn to the Lord, yet I ought not to slacken my efforts for its conversion. I have to do with my Master’s command, and what He bids me do I am bound to do…Do not forget then that there is a general opposition to the kingdom of Christ-such opposition as no human power can by any possibility overcome. ~ C.H. Spurgeon

https://www.blueletterbible.org/comm/spurgeon_charles/sermons/1007.cfm