In the play The Crucible, John Proctor faces several inner conflicts. Proctor's internal turmoil is created by the actual events of the story, but much of the play's drama springs directly from Proctor's moral anguish and in his conflicted spiritual state:
...a central theme of the play is certainly Proctor’s search for his soul.
The most important conflict for Proctor, in the end, is the choice between life and death. This choice is identical to his choice between maintaining his integrity or succumbing to the prosecution and offering a confession that would damn the others who were accused of witchcraft.
If Proctor chooses to falsely (and publically) confess to witchcraft, he will be allowed to live and to see his children grow up. If he chooses not to confess, placing his moral integrity above the value of his own life, he will be put to death.
He makes the choice that costs him his life but restores his soul.
The moment of this decision is the climax of the play.
Proctor's other inner conflicts relate to Abby and Elizabeth as he must decide how to deal with each of them. His feelings for both of them have led him to a state of conflict, though during the play this conflict is largely one of self-restraint wherein Proctor is challenged to determine how much patience he must have with Elizabeth and whether or not he can publically admit to his affair with Abigail.
These are significant conflicts in the play, but they are not as central as the final decision that will determine Proctor's ultimate moral standing.