How can duties and accountability be equal between the poor and the rich, given their differing living conditions, and why does God favor some of His servants with wealth and bliss despite the faith and devotion of others?

Objectionable thoughts about Allah's decrees are a satanic inspiration stemming from weakness of faith, not arising from a lack of evidence or proof. Such thoughts require a faith-based remedy, not argumentation.

Wealth is not the sole cause of happiness; how many rich people are miserable, and how many poor people are happy. The fundamental principle concerning divine decree is submission and acknowledgment that Allah's judgment revolves between justice and grace, and that He is wise, wrongs no one, and is not questioned about what He does.

As for the doubt concerning the equality of reckoning between the rich and the poor: wealth is often a cause for a servant's ruin, and its temptation is more severe than the temptation of poverty. The rich are required to show gratitude for things the poor are not, and perform acts of worship such as Hajj, Zakat, and financial Jihad. What the rich are given in this world is part of their accelerated reward, while the reward of the poor is stored for the Hereafter.

If a servant were to contemplate Allah's blessings upon them, they would not object to others being favored. However, their taking Allah's blessings for granted opens the doors to discontent and objection, which brings about torment of the heart.