Which of the following correctly summarizes the main point of this text from the excerpt? And a further reason for caution, in this respect, might be drawn from the reflection that we are not always sure that those who advocate the truth are influenced by purer principles than their antagonists.

Enemies will undermine those with good intentions at every turn.
In an effort this large, caution is to be remembered in all parts of the process.
Many who seem to support moral choices may also have questionable motives.
Those on the side of good will always know those who oppose them.