Does despairing of God's mercy before being afflicted with obsessive doubts necessitate apostasy from the religion, and what are the implications concerning prayer and fasting?

We advise you to ward off these whisperings by completely ignoring them and by not letting Satan lead you into thinking about them further, because the doubt of disbelief that afflicts the person suffering from whisperings is of no consequence. For he whose faith is firmly established with certainty, it cannot be removed except by certainty. Do not pay attention to Satan who whispers to you about disbelief and the nullification of your deeds.