How to perceive this world

Rex, good for you. The healthiest mental posture is a "this-worldly" religious attitude toward life. THIS and HERE are where we belong. Other-worldly religious attitudes serve only to reject our actual existence in favor of fantasies.

...simple straight and true...

I had my fair share of that sort of upbringing myself, it is not easy to overcome.
Over the years I have discovered reading to be a valuable tool in this endeavor. There are many authors who are quite skilled at presenting their humaness, of course many are not, so choosing wisely is important.
Off the top of my head a couple of the good ones are Kurt Vonnegut and Henry David Thoreau, both of which have a real knack for expressing the deepest parts of being human.
This religious "anti-worldly" view stunts our ability to relate to the social world of which you speak.

I do not think that we have to do either. Maybe we should be wary of the 'world', but by no means do we have to be sick of it. I think you are presenting a false dilemma here.

Also, what is a private perception?

Systems of belief are apparently present in this world. These beliefs range from the scientific that state we all come out of Africa and based upon physical collective scientific evidence, to beliefs in a supernatural spirit and soul that separates us from not only other unenlightened but also all other life forms.

Just because you are possibly foggy on this matter does not mean it is a false dilemma where I can see the imposed dividing line quite clearly.

Private perception, personal interpretation, one's own, thought grown in the absence of other competing thoughts, radicalism.

Radicals don't see this as a "dilemma", because they are so convinced their own side is right and "the truth"...

The dilemma is, natural versus spiritual. Religion (the spiritual side) questions and blames the human nature and provides a spiritual nature as a solution.

Religion questions the cause of illness and says it is not a physical anomaly but a spiritual malady. As we have learned in the 21 century that illness is physical and not caused by demons and devil spirits (as Jesus proposed). We also need to learn that we are all united through the physical and divided by these spiritual imaginations. And that evil does not exist... only human error and circumstance. So how do we change our nature? Is there really such a thing as human nature or is it more like instinct? Is the human nature another device and tool devised by religion to entrap us again into doubting our own validity and self.

This self awareness will rely on the physical science cures and the brains ability to cope with and repair the body. It is the brain turning on and off switches in our DNA not demonic possessions and sins of the fathers. It is evolution survival and science in a social setting.

We are one world... one unified ball of life that sprung out from the same fountain of the earth.

To superimpose spiritual causes and morality derived from superstition upon physical phenomenon is counterproductive to ever really finding the actual cause, reason, truth and answers of life.

Ironically, I couldn't download his commencement speech on my Mac.

is part of our truth instinct?

I had always thought that this kind of muddled outlook ceased at some time during, or immediatly following, the Middle Ages. Honestly. I was never, ever taught anything like that during my early religious upbringing. To look forward to rewards in the afterlife, yes, but not to, therefore, despise this one. (I was raised in the Lutheran faith, btw.)

Never taught to be ashamed of your nakedness, or offended by bodily functions?

Hell, no. I was taught that to appear naked was bad manners but certainly no mention was made of it being somehow sinful.

Have you ever wondered when and why, in the history of man, appearing naked became bad manners?

...probably when inopportune erections brought up the inner "beast" inside a pissed off "husband" !

At my age there are no "inopportune" erections.

Nope. Never wondered about that at all. Still don't.

That, apparently, happens far, far less often than one might think. I have basked on nude beaches here in Hawaii as well as on the Gulf coast of Mexico and have never seen (or experienced) any "sexual embarrasment" due to the proximity of nude members of the opposite (or same) sex. I have read and been told that any such involuntary erection is so extremely rare as to be no cause for any one's worry.

...fair and true...
...but let me just counter that we guys, in the old days, use to live up with some luck to around 35 40 years old and start a "marital" relation as soon as 14...with that age in place I would n´t bet my ass a kiddo could not suddenly get enthusiastic with some hot chick already taken over by some other Neanderthal...now if you ad up the advent of the first city´s appearance and growth with the boom in development after the neolithic, then the "maths" about the problem start to make some sense...but then it might just as well be pure speculation on my part...