Frank, the problem is not so much soap in your peehole, other than it stinging somewhat. The peehole, by the way, is medically called the meatus (me-AY-tus) and is often shaped differently in uncut guys and cut guys. I'll explain why in a moment. Inside the meatus is your urethra, which is the tube of mucous membrane through which your urine and semen come out. That's the bit that typically stings if you inadvertently get soap in it, but there's generally no damage done.
The problem with washing the glans and inner foreskin with soap, especially if you're not circumcised, is twofold: one, you have beneficial bacteria (flora) that normally live in the genital area, especially on the mucous membrane tissue (the shiny tissue). Two, that area should remain moist, covered almost all the time so the helpful flora can thrive and do their job of protecting from viral and bad bacterial pathogens. Dry mucous membrane tissue has been shown to have very little protective effect, if any; on the other hand, moist mucous membrane tissue has been shown to be a highly effective barrier against disease. This is why all the major potential entry points for germs on our bodies remain moist: mouth, eyes, anus, vagina and penis/foreskin/urethra. [The bogus studies theorizing that HIV binds to the foreskin, thus making intact men more prone to catching it, were all done on dead, severed foreskin tissue in the lab. Live foreskin tissue, with lysozymes, has the reverse effect of keeping viral infections at bay.]
Washing with soap, which is a detergent, tends to dry out this tissue and wash away the beneficial bacteria. Remember: live, healthy bacteria typically do not smell. Dead, decaying bacteria to. That's why it's important to rinse your foreskin and glans with fresh, clean, warm water every day or two. The good, live bacteria will cling to the mucous membrane surface if not washed off with soap.
Second, when mucous membrane tissue gets dried out, it changes character and becomes much more prone to fungal and yeast infections. Over time, your inner foreskin can become more dry, less elastic, and develop small cracks. The cracks may be tiny "spider" cracks or larger. These cracks can become inflamed and even infected. Believe me, a yeast infection of the foreskin is no fun. I've had one (some men have had quite a few) and it takes careful care to get that region back to normal again.
By the way, I should add here that this is also a reason that intact men should avoid most commercial lubricants, especially
those that contain any petroleum-based ingredients. I've known circumcised men who can masturbate with Vaseline Intensive Care lotion, but that is horrible on an intact penis (and precisely what inadvertently led to my yeast infection and cracking).
The drying and cracking is very significant in the foreskin area because the foreskin actually has quite a bit of muscle tissue; that's what gives it its elasticity and enables it to close snugly around a much larger glans (penis head), yet let it through when necessary. This is most pronounced in babies and little boys... their foreskins open and close like a camera lens when they pee, letting urine through and then shutting fairly tight to keep pathogens out of the urinary tract.
The foreskin is unique on all the body... there is nowhere else that the skin ends in an open, double fold of muscle tissue. It's genius engineering on nature's part.
The reason that the meatus (peehole or peeslit) is different in uncut and cut guys has to do with whether it stays covered, especially during infancy and childhood. In normal boys, the meatus is like two full, little lips that close tightly together to keep the urethra sealed. These lips get their blood supply mostly from the frenulum, the little band under the head that holds the foreskin forward. During infant circumcision the frenulum is often damaged or removed completely, affecting proper blood flow to the meatus. Also, in circumcised boys the meatus is always exposed, so it rubs against the diaper (nappy) and also gets repeatedly inflamed by diaper ammonia, feces, and other irritants. Over time, most circumcised boys lose the lips and end up with just an open hole. This hole is typically smaller than the maximal opening of the normal lips; the narrowing is called "stenosis". About 50-75% of circumcised men have meatal stenosis, but it's almost unknown among uncut guys. Meatal stenosis can be bad because it somewhat restricts the flow of uring when you pee. In children, this can cause some of the urine to flow backward toward the bladder (reflux) and contribute to urinary tract infections. It's true that you can often tell whether the guy peeing next to you is uncut or not without even looking -- circumcised men, on average, have a slightly weaker stream (because of the stenosis), whereas most uncut guys have a powerful (and therefore loud when it hits the water) stream through their larger meatus.
You can see that it's important to keep the inner foreskin and penis head clean, yet moist. Soap is a surfactant (stuff attaches to it and gets washed away) and detergent, so it's not the ideal product to use. Your penis (and anus, and inner eyelids and inside your mouth) has very different characteristics from your hands or your face, where soap (ideally a moisturising soap) can be safely used.
Just remember to save rinsing out your foreskin and glans for the last step in your shower, using only fresh water, and you should have no problems.