What is the ruling on one who is afflicted with depression and intense sadness upon seeing disbelievers fabricating lies and misguidance and mocking religions, and what will Allah do with them in this world and the hereafter?

Do not despair. Rather, sense the blessing of guidance to Islam and thank Allah for it, and rejoice in the good He has given you, as Allah says: "Say: 'In the Bounty of Allah, and in His Mercy - therein let them rejoice.' That is better than what they accumulate." Call those who are astray whom you can, and show them their misguidance, but their guidance is not your responsibility. The fate of disbelievers in the Hereafter is the Fire, wherein they will abide eternally, unless they repent. Beware of occupying yourself with specious arguments before acquiring sufficient beneficial knowledge, for hearts are weak and doubts are snatching.