He is never going to eat anything if you keep trying until he cries so much that you can't stand it. I remember when I was about 7 years old my Dad decided i was going to eat the squash we had for dinner and i started to cry and the more i cried the madder he got(I know you don't get mad at him) and finally i got a nose bleed and bled all over it and didn't have to eat it. He never tried to get me to eat anything again.
Have you ever given him anything in a spoon before? I can't imagine anyone liking that cereal made with water let alone a baby. Do you make it runny or thick?
I think you better try something else or just forget it for awhile. Maybe you could pump a little milk to mix it with or use some formula (borrow some from a friend if you don't have any).
Being of the old school we started feeding babies at 6 weeks and they would spit it out and we spooned it back in. But we put a little sugar on it!!!! so they liked it they just had no control over their tongue.
If you haven't ever had him in the high chair before try just letting him play with toys in it for a while. Maybe it isn't the food, but he doesn't like to sit there. A baby cookie or cracker might be a start.
Crazy isn't it. Some kids sit in that high chair and open their little mouths and you can't shovel it in fast enough.
Oh, if you use some formula or can pump a bottle, you can buy those special bottles that let you put in some cereal along with the milk, if you think he needs more bulk.
Have fun, love those babies of yours and enjoy these years. They will be gone before you know it.
marciab. Grandma to 11!!