Following are some quotes that you may also want to consider from L.D.S authors.
Joseph Fielding Smith, Gospel Doctrine, p.325
           Many of our young people, and some older ones, too, are not familiar with their own religion nor with the beautiful and striking doctrines of the gospel with which it is so laden. This class devote more time to reading useless or sensational books than they do to the study and contemplation of works that would familiarize them with the principles of the gospel. If they were better informed in this line, and understood the saving doctrines and every-day questions of their religion, more than they do, they would not be trapped by false teachings, false leaders, and advocates of cults that are false.

Harold B. Lee, Stand Ye In Holy Places, p.359
           The mission of this church is to bear witness of the truths of the gospel and put to flight the false teachings on every side that are causing the restlessness and the aimlessness that threaten all who have not found the straight path and that which could be an anchor to their souls.

Bruce R. McConkie, The Mortal Messiah,Vol.2, p192  p.193

We learned from Jesus as he sat on the Mount of Beatitudes, delivering his incomparable Sermon on the Mount, that we should beware of false prophets -- of the scribes and Pharisees, of the priests and Levites, who professed to be teachers and leaders and prophets but who were in fact ravening wolves in sheep's clothing. Though they wore the mantle of religious leadership, their false teachings tore apart the spiritual well-being of their flocks.

There are many L.D.S doctrines that can be proven to be in error when contrasted with the bible. However there are some issues that are more important than others. One example is pre-existence and salvation. What difference does it make if someone believes in pre-existence or not, if they are lost because of a belief in a false Christ and a false gospel? Obviously salvation is more important. I believe that the key issues should be the focal point before the minor issues when engaging in conversation concerning Mormon Doctrine. The key issues are
(1) Was Joseph Smith a true prophet of God?
(2) Does the L.D.S church teach the truth about God, Jesus or the Holy Spirit?
(3) Does the L.D.S church teach the true gospel?
(4) The L.D.S Standard Works