Why does God not guide those whom He  leaves to astray?

Verses 35-37 of Chapter 16:

The worshippers of false gods say: "If Allah had so willed, we should not have worshipped aught but Him - neither we nor our fathers,- nor should we have prescribed prohibitions other than His." So did those who went before them. But what is the mission of messengers but to preach the Clear Message? For We assuredly sent amongst every People a messenger, (with the Command), "Serve Allah, and eschew Evil": of the People were some whom Allah guided, and some on whom error became inevitably (established). So travel through the earth, and see what was the end of those who denied (the Truth). If thou art anxious for their guidance, yet Allah guideth not such as He leaves to stray, and there is none to help them.