From St. Faustina's Diary:
Fifth DaySay the Chaplet of Divine Mercy.
1218 [Jesus:] Today bring to Me the souls of heretics and schismatics, and immerse them in the ocean of My mercy. During My bitter Passion they tore at My Body and Heart; that is, My Church. As they return to unity with the Church, My wounds heal, and in this way they alleviate My Passion.
1219 [St. Faustina:] Most Merciful Jesus, Goodness Itself, You do not refuse light to those who seek it of You. Receive into the abode of Your Most Compassionate Heart the souls of heretics and schismatics. Draw them by Your light into the unity of the Church, and do not let them escape from the abode of Your Most Compassionate Heart; but bring it about that they, too, come to adore the generosity of Your mercy.
Even for those who have torn the garment of Your unity,
A fount of mercy flows from Your Heart.
The omnipotence of Your mercy, Oh God.
Can lead these souls also out of error.
Eternal Father, turn Your merciful gaze upon the souls of heretics and schismatics, who have squandered Your blessings and misused Your graces by obstinately persisting in their errors. Do not look upon their errors, but upon the love of Your own Son and upon His bitter Passion, which He underwent for their sake, since they, too, are enclosed in the Most Compassionate Heart of Jesus. Bring it about that they also may glorify Your great mercy for endless ages. Amen.