John 3:5-6 (NKJV) “Jesus answered, “Most assuredly, I say to you, unless one is born of water and the Spirit, he cannot enter the kingdom of God. 6 That which is born of the flesh is flesh, and that which is born of the Spirit is spirit.”
Matthew 9:9 (NKJV) “As Jesus passed on from there, He saw a man named Matthew sitting at the tax office. And He said to him, “Follow Me.” So he arose and followed Him.”
"Conversion is simple, very simple. Let us commence right here to come into the kingdom of heaven. How? As a little child. Just as simple as simple can be. You may get all your mysteries of the new birth, and you cannot make anybody understand it, or understand it yourself. But the best way for you is to give your mind to Jesus Christ. And the mind is the will to put it on, and do just as Matthew did. {1SAT 210.2} ... Christ said to Matthew, “Matthew, follow Me.” Did he say, “O Lord, when I get good enough I will follow you”? Did he say, “O Lord, when I have this agony, this awful agony for my sin, then I will come”? – {1SAT 211.1} Matthew rose up and followed Him." {1SAT 211.2}
"If there is nothing more in the whole Scriptures which points out definitely the way to heaven, we have it here in these words [John 3:1-16]. They tell us what conversion is. ... There is a decided change wrought in us if the truth of God has found a place in our hearts, for it has a sanctifying power upon life and upon character." {Ms 1, 1889, par. 2}
"Real conversion is a decided change of feelings and motives; it is a virtual taking leave of worldly connections, a hastening from their spiritual atmosphere, a withdrawing from the controlling power of their thoughts, opinions, and influences. The separation causes pain and bitterness to both parties. It is the variance which Christ declares that He came to bring. But the converted will feel a continual longing desire that their friends shall forsake all for Christ, knowing that, unless they do, there will be a final and eternal separation. The true Christian cannot, while with unbelieving friends, be light and trifling. The value of the souls for whom Christ died is too great. {5T 82.5} He “that forsaketh not all that he hath,” says Jesus, “cannot be My disciple.” Whatever shall divert the affections from God must be given up. Mammon is the idol of many. Its golden chain binds them to Satan. Reputation and worldly honor are worshiped by another class. The life of selfish ease and freedom from responsibility is the idol of others. These are Satan’s snares, set for unwary feet. But these slavish bands must be broken; the flesh must be crucified with the affections and lusts. We cannot be half the Lord’s and half the world’s. We are not God’s people unless we are such entirely." {5T 83.1}
"Genuine conversion is a grand and noble thing. It means leaving childish things behind, and being a man, one with Christ as Christ is one with the Father, the faith clinging to Christ, the friend of sinners.” {Lt66-1899.6}
"True conversion is a change from selfishness to sanctified affection for God and for one another." {1SM 115.1}
"Conversion is a work that most do not appreciate. It is not a small matter to transform an earthly, sin-loving mind and bring it to understand the unspeakable love of Christ, the charms of His grace, and the excellency of God, so that the soul shall be imbued with divine love and captivated with the heavenly mysteries. When he understands these things, his former life appears disgusting and hateful. He hates sin, and, breaking his heart before God, he embraces Christ as the life and joy of the soul. He renounces his former pleasures. He has a new mind, new affections, new interest, new will; his sorrows, and desires, and love are all new. The lust of the flesh, the lust of the eye, and the pride of life, which have heretofore been preferred before Christ, are now turned from, and Christ is the charm of his life, the crown of his rejoicing. Heaven, which once possessed no charms, is now viewed in its riches and glory; and he contemplates it as his future home, where he shall see, love, and praise the One who hath redeemed him by His precious blood. {2T 294.2} The works of holiness, which appeared wearisome, are now his delight. The word of God, which was dull and uninteresting, is now chosen as his study, the man of his counsel. It is as a letter written to him from God, bearing the inscription of the Eternal. His thoughts, his words, and his deeds are brought to this rule and tested. He trembles at the commands and threatenings which it contains, while he firmly grasps its promises and strengthens his soul by appropriating them to himself. The society of the most godly is now chosen by him, and the wicked, whose company he once loved, he no longer delights in. He weeps over those sins in them at which he once laughed. Self-love and vanity are renounced, and he lives unto God, and is rich in good works. This is the sanctification which God requires. Nothing short of this will He accept." {2T 294.3}
"When the sinner sees Jesus lifted upon the cross, dying that he might not perish but have everlasting life, he realizes something of the enormity of sin, and longs for pardon for all his transgressions, and for the favor of God. ... He rejoices in the pardoning love of God, and his sincerity in the service of God, the reality of his conversion, is made manifest by the vigor of his endeavor to obey all of God’s commandments. The soul who has found the Lord will renounce every evil work, will cease to do evil and learn to do well, because Christ is formed within the hope of glory." {Ms40-1894.24}
"A man is no sooner converted than in his heart is born a desire to make known to others what a precious friend he has found in Jesus.” {4T 318.3}
"Candidates who have grown to manhood and womanhood should understand their duty better than do the younger ones. ... Show what is the fruit of conversion, the evidence that they love God. Show that true conversion is a change of heart, of thoughts and purposes. Evil habits are to be given up. The sins of evil-speaking, of jealousy, of disobedience, are to be put away. A warfare must be waged against every evil trait of character." {CCh 297.3}
"Lead the people to look to Jesus as their only hope and helper; leave the Lord room to work upon the mind, to speak to the soul, and to impress the understanding. It is not essential for you to know and tell others all the whys and wherefores as to what constitutes the new heart, or as to the position they can and must reach so as never to sin. You have no such work to do. {1SM 177.3} All are not constituted alike. Conversions are not all alike. Jesus impresses the heart, and the sinner is born again to new life. Often souls have been drawn to Christ when there was no violent conviction, no soul rending, no remorseful terrors. They looked upon an uplifted Saviour, they lived. They saw the soul’s need, they saw the Saviour’s sufficiency, and His claims, they heard His voice saying, “Follow Me,” and they rose up and followed Him. This conversion was genuine, and the religious life was just as decided as was that of others who suffered all the agony of a violent process." {1SM 177.4}
"Our ministers must cease to dwell upon their peculiar ideas with the feeling, “You must see this point as I do, or you cannot be saved.” Away with this egotism. The great work to be done in every case is to win souls to Christ. Men must see Jesus on the cross, they must look and live. It is not your ideas they must feed upon, but it is the flesh and blood of the Son of God. He says, “My flesh is meat indeed.” “The words that I speak unto you, they are spirit and they are life.” [John 6:55, 63.] {Lt 15a, 1890, par. 8} Christ, the Physician of the soul, understands its defect and its maladies and knows how to heal with the purchase of His own blood. What the soul lacks, He can best supply. But men are so officious, they want to do so much, that they overdo the matter, leaving Christ no room to work. {Lt 15a, 1890, par. 9} ... God in Christ is daily beseeching men to be reconciled to God. With outstretched arms He is ready to receive and welcome, not only the sinner but the prodigal. His dying love, manifested on Calvary, is the sinner’s assurance of acceptance, peace, and love. Teach these things in the simplest form, that the sin-darkened soul may see the light shining from the cross of Calvary." {Lt 15a, 1890, par. 11}
"Christ does not weigh character in the scales of human judgment. He says, “I, if I be lifted up from the earth, will draw all men unto me.” John 12:32. Every soul who responds to this drawing will turn from iniquity. Christ is able to save to the uttermost all who come unto Him. He who comes to Jesus is setting his feet upon a ladder that reaches from earth to heaven. Teach it by pen, by voice, that God is above the ladder; the bright rays of His glory are shining upon every round. He is looking graciously upon all who are climbing painfully upward, that He may send them help, divine help, when the hand seems to be relaxing and the foot trembling. Yes, tell it, tell it in words that will melt the heart, that not one who will perseveringly climb the ladder will fail of an entrance into the everlasting kingdom of our Lord and Saviour Jesus Christ; those who believe in Christ shall never perish, neither shall any pluck them out of His hand. {Ms 82, 1894, par. 32} Tell the people in clear, hopeful language how they may escape the heritage of shame which is our deserved portion. But for Christ’s sake do not present before them ideas that will discourage them, that will make the way to heaven seem very difficult. While we must often impress the mind with the fact that the Christian life is a life of warfare, that we must watch and pray and toil, that there is peril to the soul in relaxing spiritual vigilance for one moment, the completeness of the salvation proffered us by Jesus, who loved us and gave Himself that we should not perish but have everlasting life, is to be our theme." {Ms 82, 1894, par. 33}
"Some workers in the cause of God have been too ready to hurl denunciations against the sinner; the grace and love of the Father in giving His Son to die for the sinful race have been put in the background. The teacher needs the grace of Christ upon his own soul, in order to make known to the sinner what God really is—a Father waiting with yearning love to receive the returning prodigal, not hurling at him accusations in wrath, but preparing a festival of joy to welcome his return (Zephaniah 3:14-17). {1SM 184.1} ... You cannot gain an entrance by penance nor by any works that you can do. No, God Himself has the honor of providing a way, and it is so complete, so perfect, that man cannot, by any works he may do, add to its perfection. It is broad enough to receive the greatest sinner if he repents, and it is so narrow, so holy, lifted up so high, that sin cannot be admitted there." {1SM 184.3}
"If you have Christ abiding there, you cannot fret or scold. You cannot make others unhappy and wretched and miserable. No. Because Christ is there, His joy is there, His peace is there. You want everybody to have peace; you want them to have comfort; you want them to have good hope; you want them to have courage, and you keep talking of Jesus and His love—what He has done for me." {1SAT 207.1}199.1}
Pastor E. L. Minchin wrote a very helpful article on the topic of conversion that you may find helpful.