Alas my kids are all mostly grown up (relative to yours) and my number 3 just got his first real road bike.

Advice: throw the bike in the car, drive about 3 miles away drop him off with the bike and start to drive away. He'll learn pretty quick...it is very similar to teaching a kid to swim, just throw him in and either let him inhale some water, or learn to stay up...it is amazing how quickly they get it.

In all seriousness. There have been some great suggestions up above. But I must say for now: Dad, step away from the bike, you sound a little wound up, and your little guy can sense that. He is probably desperately trying to please you, and combined with the stress, it is just not working yet. Back off, go out and play catch instead. He will pick it up when he is ready, could be tomorrow, could be next summer, don't worry he won't be going off to college not able to ride .