Mark 8:14-21

 Now they had forgotten to bring bread, and they had only one loaf with them in the boat.  And he cautioned them, saying, “Watch out; beware of the leaven of the Pharisees and the leaven of Herod.”  And they began discussing with one another the fact that they had no bread.  And Jesus, aware of this, said to them, “Why are you discussing the fact that you have no bread? Do you not yet perceive or understand? Are your hearts hardened?  Having eyes do you not see, and having ears do you not hear? And do you not remember?  When I broke the five loaves for the five thousand, how many baskets full of broken pieces did you take up?” They said to him, “Twelve.”  “And the seven for the four thousand, how many baskets full of broken pieces did you take up?” And they said to him, “Seven.”  And he said to them, “Do you not yet understand?” Mark 8:14-21

Let us notice the solemn warning which our Lord gives to His disciples at the beginning of this passage. He says, "Take heed, beware of the leaven of the Pharisees and of the leaven of Herod."

We are not left to conjecture the meaning of this warning. This is made clear by the parallel passage in Matthew's Gospel. We there read that Jesus did not mean the leaven of "bread," but the leaven of "doctrine." The self-righteousness and formalism of the Pharisees — the worldliness and skepticism of the courtiers of Herod, were the object of our Lord's caution. Against both He bids His disciples be on their guard.

Such warnings are of deep importance. It would be well for the Church of Christ, if they had been more remembered. The assaults of persecution from without have never done half so much harm to the Church, as the rise of false doctrines within. False prophets and false teachers within the camp have done far more mischief in Christendom than all the bloody persecutions of the emperors of Rome. The sword of the foe has never done such damage to the cause of truth as the tongue and the pen.

The doctrines which our Lord specifies, are precisely those which have always been found to inflict most injury on the cause of Christianity. Formalism on the one hand, and skepticism on the other, have been chronic diseases in the professing Church of Christ. In every age multitudes of Christians have been infected by them. In every age men need to watch against them, and be on their guard.

The expression used by our Lord in speaking of false doctrine is singularly forcible and appropriate. He calls it "leaven." No word more suitable could have been employed. It exactly describes the small beginnings of false doctrine — the subtle quiet way in which it insensibly pervades a man's religion — the deadly power with which it changes the whole character of his Christianity. Here, in fact, lies the great danger of false doctrine. If it approached us under its true colors, it would do little harm. The great secret of its success is its subtlety and likeness to truth. Every error in religion has been said to be a truth abused.

Let us often "examine ourselves whether we be in the faith," and beware of "leaven." Let us no more trifle with a little false doctrine, than we would trifle with a little immorality or a little lie. Once admit it into our hearts, and we never know how far it may lead us astray. The beginning of departure from the pure truth is like the letting out of waters — first a drop, and at last a torrent. A little leaven leavens the whole lump. (Gal. 5:9.)

Let us notice the dull understanding of the disciples, when our Lord gave the warning of this passage. They thought that the "leaven" of which He spoke must be the leaven of bread. It never struck them that He was speaking of doctrine. They drew from Him the sharp reproof — "Perceive you not yet, neither understand? are your hearts hardened? How is it that you do not understand?" Believers, converted, renewed, as the disciples were, they were still dull of apprehension in spiritual things. Their eyes were still dim, and their perception slow in the matters of the kingdom of God.

We shall find it useful to ourselves to remember what is here recorded of the disciples. It may help to correct the high thoughts which we are apt to entertain of our own wisdom, and to keep us humble and lowly-minded. We must not fancy that we know everything as soon as we are converted. Our knowledge, like all our graces, is always imperfect, and never so far from perfection as at our first beginning in the service of Christ. There is more ignorance in our hearts than we are at all aware of. "If any man think that he knows anything, he knows nothing yet as he ought to know." (1 Cor. 8:2.)

Above all, we shall find it useful to remember what is here recorded, in dealing with young Christians. We must not expect perfection in a new convert. We must not set him down as graceless and godless and a false professor, because at first he sees but half the truth and commits many mistakes. His heart may be right in the sight of God, and yet, like the disciples, he may be very slow of understanding in the things of the Spirit. We must bear with him patiently, and not cast him aside. We must give him time to grow in grace and knowledge, and his latter end may find him ripe in wisdom, like Peter and John. It is a blessed thought that Jesus, our Master in heaven, despises none of His people. Incredible and blameworthy as their slowness to learn undoubtedly is, His patience never gives way. He goes on teaching them, "line upon line, precept upon precept." Let us do likewise. Let it be a rule with us never to despise the weakness and dullness of young Christians. Wherever we see a spark of true grace, however dim and mixed with infirmity, let us be helpful and kind. Let us do as we would be done by.