People might carry around plenty of religious beliefs, but they don't think they're actually realistic in many cases. They're just "my beliefs" and it doesn't go beyond that.
I think what you are saying is that it takes more than 'belief' to motivate actions. Sunday Christians, for example, may have some vague, unexamined belief in an afterlife of rewards and punishments -but it doesn't effect their overall conduct the other six days of the week. They still behave is as this
life is all that really matters. Western Buddhists tend to do something similar with the belief in rebirth. They say they believe in reincarnation, and maybe they do, but they don't do anything to invest in their next incarnation. Is this what you mean? If so, I agree. But such a thing is inevitable in a country with a good standard of living like America. People with every pleasure on their table aren't going to risk forfieting what they can see for what they can't and, from their perspective, such an an attitude is very reasonable.
why give up worldly pursuits on a risky venture such as enlightenment and liberation from samsara?
I wish I can remember the exact sutra I read this in but I do seem to remember a snippet of dialogue between Shakyamuni and one of his disciples that went something like this (forgive my paraphrasing).
DISCIPLE: What if I don't believe in a life after this one. Why persue to nirvana?
SHAKYAMUNI: For those who don't believe in rebirth, I offer freedom in this life. For those who do believe in rebirth, freedom in this life as well as the next.
Of course, it takes a certain amount of insight (not to mention experience) to realize the vanity of most worldly pursuits but for those who can see that vanity, Buddhism offers a way to overcome it. What really impressed me about Buddhism and caught my interest is the figure of Buddha himself:
Shakyamuni was not some poverty stricken carpenter like Jesus who may as well of made a virtue of his inescapable poverty. Shakyamuni was a prince. Everything a mortal might reasonably desire was his for the asking. He could indulge in any luxury. Could eat any food, as much of it as he wanted. He had his choice of sexual partners and could indulge any fetish, no matter how taboo. Even if he wasn't so carnally minded, he must have at least had intellectual or athletic ambitions. As a prince he could hire the greatest tutors in India to teach him and make him an expert in whatever subject or art he was bold enough to pursue mastery of. Do you understand? He could have had anything
. But at the age of 29 he gives it all up and becomes a homeless yogi. Now you may think: "Well, maybe Shakyamuni was just having a midlife crises". Maybe so. That's what I would think. But he keeps at it. After he attains nirvana he still, presumably, could put his crown back on and return to a life of virtual omnipotence. But he doesn't. Whatever nirvana is, apparently it is so damn good that all the wealth, fame, sex, and power in the world cannot compare to it!
THAT'S what initially sparked my interest in Buddhism. Not some void in my life left after materialism ripped away my spiritual center, and I think that may be what lures many westerners to Buddhism. It's not the stick of samsara, but the carrot of nirvana that goads us greedy materialists! Hence, unless you are a Pure Land Buddhist, rebirth becomes rather irrelevant. You're gonna bust your ass right now
in this life so you can attain nirvana and then enjoy it as soon as possible! Now if you die in the process and don't attain you may, it's true, have foregone some fleeting, piss ant pleasures for nothing. But then, if you are discontent enough to even dedicate a second thought to something beyond
these piss ant worldly pleasures then chances are they weren't going to bring you much happiness in the first place.
My point is that while a belief in rebirth can be a goad; it isn't the only one. You don't have to believe in any afterlife to see this pointless, rat-race-to-the-gutter 'life' for what it is. Nietzsche was a hardcore materialist but he spoke very eloquently of it in Thus Spake Zarathustra
Yea, a dying for many hath here been devised, which glorifieth itself as life: verily, a hearty service unto all preachers of death!
The state, I call it, where all are poison–drinkers, the good and the bad: the state, where all lose themselves, the good and the bad: the state, where the slow suicide of all—is called “life.”
Just see these superfluous ones! They steal the works of the inventors and the treasures of the wise. Culture, they call their theft—and everything becometh sickness and trouble unto them!
Just see these superfluous ones! Sick are they always; they vomit their bile and call it a newspaper. They devour one another, and cannot even digest themselves.
Just see these superfluous ones! Wealth they acquire and become poorer thereby. Power they seek for, and above all, the lever of power, much money—these impotent ones!
See them clamber, these nimble apes! They clamber over one another, and thus scuffle into the mud and the abyss.
Towards the throne they all strive: it is their madness—as if happiness sat on the throne! Ofttimes sitteth filth on the throne.—and ofttimes also the throne on filth.