Based on what characteristics of people does God decide to lead them astray or guide to the straight path?

 

Verses 26-27 of Chapter 2:

Well, Allah is not ashamed to cite the similitude of a gnat or of something even more insignificant than this. As for those who believe, they come to know from the same similitude that it is the Revelation from their Lord; but those who disbelieve, say, "What does Allah mean by such similitudes?"Allah leads astray many and guides many to the right way by the same thing. And He leads astray only those who disobey Allah; who break Allah's covenant after ratifying it; who cut asunder what Allah has ordered to be joined,and who produce chaos on the Earth.These are the people who are indeed the losers.

Verses 15-16 of Chapter 5:

O People of the Scripture! Now has come to you Our Messenger explaining to you much of that which you used to hide from the Scripture and passing over much. Indeed, there has come to you from Allah a light and a plain Book. Wherewith Allah guides all those who seek His Pleasure to ways of peace, and He brings them out of darkness by His permission unto light and guides them to a straight path.

 Verses 125-127 of Chapter 6:

So (the fact is that) whomsoever Allah wills to guide aright, He makes his breast wide open to Islam, and whomsoever He wills to let go astray, He makes his breast narrow and squeezes it so tight that (at the very idea of Islam) he begins to feel as if his soul were climbing up towards the sky. Thus Allah sets the impurity (caused by their deviation from the Way of Islam) over those who do not believe, whereas this Way is the Straight Way of your Lord, and We have made its signs quite clear for those who are amenable to advice. There is an abode of peace or them with their Lord, and He is their Protector because of the good works they are doing. 

Verses 146-147 of Chapter 7:

I shall turn away from My Ayat those who behave arrogantly on the earth, without a right, and (even) if they see all the Ayat, they will not believe in them. And if they see the way of righteousness, they will not adopt it as the way, but if they see the way of error, they will adopt that way, that is because they have rejected Our Ayat and were heedless of them. Those who deny Our Ayat and the meeting in the Hereafter, vain are their deeds. Are they requited with anything except what they used to do.