Moroni 10:32 reads as follows:
Yea, come unto Christ, and be perfected in him, and deny yourselves of all ungodliness; and if ye shall deny yourselves of all ungodliness, and love God with all your might, mind, and strength, then is his grace sufficient for you, that by his grace ye may be perfect in Christ; and if by the grace of God ye are perfect in Christ, ye can in nowise deny the power of God.
These words are mirrored in another work authored by Moroni in Ether 12:26-27:
And when I had said this, the Lord spake unto me, saying, Fools mock, but they shall mourn; and my grace is sufficient for the meek, that they shall take no advantage of your weakness; And if men come unto me I will show unto them their weakness. I give unto men weakness that they may be humble; and my grace is sufficient for all men that humble themselves before me; and if they humble themselves before me, and have faith in me, then will I make weak things become strong unto them.
Some critics of LDS theology holds that this is a command and that LDS theology is “salvation: mission impossible.” Funny thing is that many of these critics hold to the Bible being the infallible, inerrant word of God, the same text which contains texts such as Matt 22:37 (cf. Mark 12:30; Luke 10:27):
Jesus said unto him, Thou shalt love the Lord thy God with all thy heart, and with all thy soul, and with all thy mind.
In reality, such texts and similar ones in the New Testament are aspirational, similar to Moroni 10:32.
Just consider the following quotes:
In the Bible, Christ says "follow me", "be ye therefore perfect", “sell all and give”, and keep my commandments". Like the Moroni 10 passage you ask about, these commands seem quite absolute, but they are just as easily understood to be aspirational in nature. (Stephen E. Robinson, Believing Christ, 89-90).
Evangelical Christian scholar Millard Erickson says something similar:
Certain difficulties attach to assuming [we can achieve freedom from sin], however. One is that it seems contradictory to repeatedly exhort Christians to a victorious spotless life unless it is a real possibility. But does this necessarily follow? We may have a standard, an ideal, toward which we press, but which we do not expect to reach within a finite period of time. It has been observed that no one has ever reached the North Star by sailing or flying toward it. That does not change the fact that it is still the mark toward which we press, our measure of “northerliness.” Similarly, although we may never be perfectly sanctified within this life, we shall be in eternity beyond and hence should presently aim to arrive as close to complete sanctification as we can.” (Christian Theology. p. 986)
Therefore, Moroni 10:32 in the Book of Mormon should be interpreted as one interprets similar admonitions in the Bible, that is, they should be understood, not as prerequisites for salvation, but as goals reflecting God's standards.