What does the Bible say about sincerity?

It means literally "one-foldedness" or "simplex structure." We are all familiar with the annoying experience of seeing objects distorted through a common sheet glass window. Light travels slower in glass than in air and in passing through the thicker parts of the glass is retarded so that the wave front of the light becomes bent and clear vision is impossible. The Scriptural meaning of the word is then that there should be no ulterior motive or duplicity in the Christian's action, indeed, he should be what is commonly termed "transparently honest." The perfect example in this as in every other respect was presented in the Lord Jesus Christ and what was true in Him while He was here, should now be true in the Christian.

Surely if ever there was a day when the people of God needed to be aroused to this it is the present time. What mixing of the precious and the vile there is! What contact of holy with unholy! (See Jeremiah 15:19, and Haggai 2:12-13.) Still the exhortation is given to us by the Spirit of God, "Let us keep the feast … with the unleavened bread of sincerity and truth." Sincerity means for us true uprightness of heart. No unworthy motives are to be allowed to work in the mind and heart, no guile nor duplicity practised, no assuming of an outward position or manner, which is not in keeping with the desire and purpose of our hearts. We are to be affected and formed by the truth in all the moral springs from which our actions flow; for the truth has a sanctifying, cleansing action on the heart and thoughts, when we submit ourselves to its operation. Then, practically cleansed by the word and Spirit of God from all that is defiling and unsuitable to the presence of our God, we are free to keep the feast "with the unleavened bread of sincerity and truth." S. M. A.

It is worth noting here that this feast springs out of and is connected with the feast of the passover. The usual introduction to a new subject, namely "the LORD spake to Moses saying," is not mentioned here. This feast then is the corollary of the passover. It is the putting away of all evil because Christ has died to sin once. Rom. 6:10. It is the subjective answer in us to the objective work of Christ on the cross. If He has died to sin, then we must die to it in a practical way in our Christian pathway. "For even Christ our passover is sacrificed for us: Therefore let us keep the feast, not with old leaven, neither with the leaven of malice and wickedness; but with the unleavened bread of sincerity and truth." 1 Cor. 5:7-8. Here, the feast of unleavened bread is seen as the direct outcome of the feast of the Passover. Hence, the Spirit exhorts them to keep from leaven altogether. He speaks of the leaven in two ways. First as old leaven, then as malice and wickedness. The first would be a reference to their old way of living before the Gospel reached them. Possibly a reference to the worship of idols and the notorious fornication which accompanied it. To them this was "old leaven." The leaven of malice and wickedness would spring from the old man which was still in them. This too had to be refused, for while they might break with the fornication of idol worship they carried with them the old man whose malice and wickedness would be ever ready to spring out. Both had to be put away. But if these two evils had to be refused, sincerity and truth had to be accepted. This would be Christ as ministered to my soul by the Spirit. I am then to be done with my old way of living. Secondly, I am to keep the old man with his deeds in subjection. Thirdly, I am to feed upon Christ as food for my soul and so I grow to be like Him, sincere and true.

Now, therefore, says Joshua, having recounted the wonderful ways of the Lord to and for His people. "Now therefore fear the Lord, and serve Him in sincerity and in truth: and put away the gods which your fathers served on the other side of the flood, and in Egypt; and serve ye the Lord." Departure from God and idolatry are sins that are a very part of man's fallen nature; and occupation of a position, though the most favoured, will not keep departure from God and idolatry out of the heart. It is vain to argue that no hidden household gods were in the houses of Israel, because the nation was in Canaan, and surrounding the tabernacle at Shiloh with its glory-cloud. The call to purge themselves was of God, who knew where the idols were hidden.

1866 120 Rectitude of heart and the truth always go together. This is seen in Christ, who was Himself the Truth — it was in Him, and He was it; but we must always know in part. In Christ alone was there perfect reality, sincerity; and we have sincerity in so far as we have Him. Where Christ is not there is no sincerity — that is reality. There may be what men call sincerity, where the heart is dark, and has been badly taught; but in this case there cannot be reality, for the truth only is real.

Observe, I do not charge you with being hypocrites, for I do not say that Cain was not sincere. There is no doubt indeed of his sincerity; but then his sincerity only evidenced the blind-hardness of his heart. Human sincerity means nothing, it is often but the greatest proof of the desperate darkness in which a man is. Those were sincere of whom Christ said, "He that killeth you will think he doeth God service." Saul of Tarsus was thoroughly sincere when he "thought" he "ought to do many things contrary to the name of Jesus of Nazareth." He consulted moreover the chief priests and elders, the religious authorities of the day. He was zealous for his religion, and thoroughly sincere as a man, but totally blind as to God and the things of Christ, thinking to do God service by fighting against and slaying His saints. Cain, in his sincerity, brought to the Lord that which cost him something, that which was the fruit of his toil. He came to God as a worshipper, and in so doing offered to God that which he had brought honestly as a man, but which proved him to be ignorant of his state as a sinner.

Observe, I do not charge you with being hypocrites, for I do not say that Cain was not sincere. There is no doubt indeed of his sincerity; but then his sincerity only evidenced the blind hardness of his heart. Human sincerity means nothing; it is often but the greatest proof of the desperate darkness in which a man is. Those were sincere of whom Christ said, "He that killeth you will think he doeth God service." Saul of Tarsus was thoroughly sincere when he thought he "ought to do many things contrary to the name of Jesus of Nazareth." He consulted moreover the chief priests and elders, the religious authorities of the day. He was zealous for his religion, and thoroughly sincere as a man, but totally blind as to God and the things of Christ, thinking to do God service by fighting against and slaying His saints. Cain in his sincerity brought to the Lord that which cost him something, that which was the fruit of his toil. He came to God as a worshipper, and in so doing offered to God that which he had brought honestly as a man, but which proved him to be ignorant of his state as a sinner.

If there is one Christian virtue that is wholesome and safe it is sincerity—to be real, true, without veneer, in all places and at all times. This will be so, if we are consciously in the presence of God.

sincerity cannot save the soul.

Counterfeit piety is double iniquity. A little rusty gold is far better than a great deal of bright brass. A little true grace, though rusted over with many infirmities, is better than all the glistering shows of hypocrites. … The hypocrite is fair to look on, he has a devout eye but a hollow heart; but he who is sincere, his inside is his best side.