Kudos for those who listened to your question - Denise P and MR.
Sometimes we don't have the choice and formula is what we have to do. It is a hard transition for some children. People who say formula is poison are just being un-sympathetic to those of us who had no choice. wow-It really makes me said to see people not be supportive to all moms. It's a tough job already with out having to be criticized by another mom. Sorry you got some of that on here.
Was he taking a bottle before? Because that could be some of the issue. If so, maybe try having someone else do the feeding, if possible. If bottle is new, then maybe try a different kind. Maybe try another type of formula. I would keep offering as it sounds like it might be your only choice. And chances are most likely he will eventually take it. You could offer nursing, if possible maybe just in the morning and in the evening to help slowly offer the transition. And definitely keep up with the solid food mix with formula. That is a good way to get the benefit from it too. Also, maybe have a chat with his DR for some advice.
I babysat for a little one who had never been fed a bottle until the day I got him. Even though his mother was able to pump and provide enough bottles, he wouldn't even take the bottle. It took a good solid 4 days until he would finally take that bottle. I felt horrible for him and his mom and me too. It is tough.
I don't know if you saw the blog on Mamapedia today - it was about eating and although it was geared to a toddler, it was a great article that explained children and their eating patterns and how change isn't easy to accept....
Good luck to you - from another mom who had to make the same choice as you. :-)