A woman confesses to the Elder Zossima that she is struggling with doubts regarding her faith, she is having trouble because she cannot prove her religion to herself and she begs the elder to teach her how to convince herself. The Elder responds:
...there's no proving it, though you can be convinced of it. By the experience of active love. Strive to love your neighbor actively and indefatigably. In as far as you advance in love you will grow surer of the reality of God and of the immortality of your soul. If you attain to perfect self-forgetfulness in the love of your neighbor, then you believe without doubt, and no doubt can possibly enter your soul. This has been tried. This is certain.
Dostoevsky on Doubt/ The Brothers.