Matthew 18:6

6. Shall offend The word offend, at the present day, signifies to irritate or make angry. It here, however, signifies to cause to sin or to apostatize. It is to make one offended with Christ. Hence, as on the one hand he who receives, or cherishes, the humble Christian receives Christ himself; so he who causes the humble Christian to lose his religion and his soul, renders himself liable to unutterable condemnation. See note on Matthew 18:7.

A millstone were hanged about his neck… drowned The millstone here specified was not the domestic hand-stone, turned by women, in grinding. See note on Matthew 24:41. Besides this there was among the Jews the heavy sort, of which the upper stone was turned by the ass, and hence in the original called the ass-millstone. Hanged about his neck to secure his sinking. In the depth of the sea In the main centre of the sea. The capital punishments among the Jews were either burning, stoning, strangling, or beheading. Drowning was and is prevalent among other Eastern nations, and it existed even among the Greeks. This was said to be the punishment for the crime of sacrilege, to which the crime of seducing a soul from Christ is analogous. The intensity of the depth is described as the image of the utter ruin which his crime deserves. It of course implies that he perishes under the divine displeasure, and receives from God the depth of punishment of which the human penalty is so apt an image. Indeed, the whole must be figurative. Our Lord could not mean that in any case a civil or state punishment would be inflicted upon the man who should cause a Christian to fall into sin.