Some had one or both of their parents threaten to take their...
Some had one or both of their parents threaten to take their lives and the lives of their offspring in order to deflect them from diving deeper into their belief. For those who remain in iman is the promise that they will come to know Allah and the truth of the Resurrection. The more they exert themselves in this life, the closer they will get to this state of knowledge. The mu'minun (believers) are given a clear code of conduct. By righteously doing their utmost they will be amply rewarded.
8 And We have enjoined on man goodness to his parents, and if they contend with you that you should associate (others) with Me, of which you have no knowledge, do not obey them; to Me is your return, so I will inform you of what you did. 9 And (as for) those who believe and do good, We will most surely cause them to enter among the good. The first thing a child witnesses is his parents. If he does not show loyalty towards them, he cannot show loyalty in a subtler way towards Allah.
A child's rebellion against his parents is a rebellion against all those who have physical power over him and sustain him. If a child is rebellious against his parents, he is likely to be rebellious against anything. The parents may be, from a spiritual point of view, misguided, but the child can only be qualified to reflect upon or witness that when his own self-guidance begins to emerge. Irrespective of anything, the child should have compassion for them.
Under all circumstances, a person is advised to be respectful to his parents. It does not mean he is to be under their domination, but when their names are mentioned, he should ask for their forgiveness. After all, they were the means by which he had come about. Regardless of whether one is good or bad one still has the mercy of the Creator upon him. Allah is the invisible origin from which man has come forth through his parents. There are various degrees of iman.
A true mu'min regards everything that happens to him as his destiny. It must be, for it has occurred and is itself the proof of its truth and reality. It has occurred not out of a whim but from Reality. A mu'min takes knowledge from everything, whether it appears to be good or bad. If he has not identified himself with a specific, fixed viewpoint, he will derive knowledge and benefit from affliction.