SP 275 - The purification of the soul is accomplished through Love and Truth. They give birth to perfect contrition, and this purifies from all evil. The heart becomes pure when it is filled with Love and Truth. Love enables it to make every sacrifice, and Truth gives birth to humility, and this is holiness.

SDD 391 - The purification of the soul must hurt. Then it is true and lasting.

SDD 727 - The purification of your soul will last until the end of your life and will reach deeper and deeper layers - so that I can fill you ever more.

Alice: You sentenced man to pain by giving him such a nature.
JESUS: To short pain and to eternal joy - if he is willing to accept it.
With Me you will learn the Truth in its entirety. Now you know only fragments of it, so that you can gain merit resulting from faith.