How do we reconcile the wisdom behind sending messengers being to establish proof against people, and guidance being from Allah, based on His saying: "He whom Allah guides is the [rightly] guided; but he whom He sends astray - then it is those who are the losers," and His saying: "Messengers who gave good tidings and warning so that mankind will have no argument against Allah after the messengers"?

Guidance and misguidance are in the hands of Allah, yet the servant is the one who is misguided or guided.

The two main levels of guidance are: the guidance of clarification and indication (specific to those held accountable), and the guidance of divine grace (which only Allah can grant).

Allah's argument against His servants is established by His clarification, His sending of messengers, and His providing them with apparent and hidden means of guidance. So, nothing came between them and what was within their capacity, but rather, something came between them and His action, His will, and His divine grace.

Allah has linked everything to causes. Thus, guidance and misguidance have their causes, and humans have been given will and choice to weigh between options.

Allah sent messengers and revealed books to clarify the truth and guide people. This guidance is general for all beings and does not necessitate that everyone who receives it will attain divine grace.

Allah's misguiding of those who go astray comes as a punishment for their actions, which originated from their choice and will, after they turned away and disbelieved out of stubbornness and denial.

In conclusion, Allah sent messengers for clarification, and the disbeliever chooses disbelief by their will, just as the believer chooses faith by their will.