The process for transmitting this official doctrinal message to Moroni is important. Mormon appears to have the position of leader of the church, what we would call the President (although there is no indication that Nephites ever used that type of title). As the leader, Mormon still understood that the true head of the Church is Christ, and therefore the question is posed in prayer. What comes is revelation, and Mormon passes the information to his son as a declaration of authority from Christ.
The actual revelation is given in verse 8. It is a pretty simple declaration that the function of the atonement, and therefore the attendant baptism, is a commitment to repentance and a covenant of entrance and discipleship. Christ declares: “the whole need no physician.” Thus, the atonement operates on those who are in need, not those upon whom there is no need. Little children qualify as having no need, “for they are not capable of committing sin.” There are two aspects of the atonement. The first, which is the physical death, or the inheritance of Adam, is removed through the universal atonement. It is the second death, spiritual death, which is in question here. That type of “death” occurs through separation from God through sin. Little children are not capable of sin; therefore, there is no need for that part of the atonement as regards to little children. It is that part of the atonement that baptism recalls.
Verse 9 makes it clear that the concept of political correctness was not present in Mormon’s day. It is a harsh statement that baptizing little children “is solemn mockery before God.” Nevertheless, that is what he said. We should understand why he said that. In short, it is because it is contrary to the reason for which baptism was instituted, hence contrary to God’s plan. Mormon will have something similar to say in verse 16 of this chapter.