From the centuries of histories of lives that have come and gone, there has never been given a satisfactory answer. We are surrounded by mysticism, mechanistic existentialism (despairingly), and attempts of combining the two.
As each person seeks his own understanding, a personally unique philosophy develops and each one finds that he can live with this rationale, regardless of whether or not it seems rational to others.
Quite often in trying to reassure oneself that one's rationale is correct, one will present it to another. If another agrees, one feels “kinship” and also feels self-justified. They may share their rationale with others and a group of believers may develop. If this rationale is in conflict with another person's rationale, insecurities may arise as one's “belief system” is threatened. At this point defenses may flare and self-righteousness may prevail. Groups of people with similar beliefs use their numbers to argue that they are right. (“If we are wrong, then why are there so many of us?”)
We now exist in a world which consists of many philosophical and theological groups that avow that their way is the right way. Upon closer examination of philosophical and theological communities, it is easily seen that factions develop within each group, and factions within the factions and individuals within the factions each pick and choose that which is acceptable and palatable, and that which is not, according to one's own personally developed individual belief system. And “individually” is where it all started.
It appears to the outside observer not involved with the process of existence justification that there is an awful lot of rigmarole about something that should have been left to the individual from the beginning.
If one eliminates the mysticism and propaganda from historical accounts of past lives that have become central figures of our cultural belief systems, you can draw great examples of how to live your life with fulfillment. You are only in control of “your” attitude about life and “your” perception of your purpose in life.
Understanding this does not change the way that the world exists. You must realize and understand that the world is caught up in a whirlwind of philosophies and theologies and to challenge them, as history teaches, can bring about your own demise.
Seek your own individual truths and embrace them. Respect others' right to do the same.