A lot of toddlers throw tantrums and fight diaper changes and you're certainly not alone in this.
There's many reasons that your toddler is throwing a tantrum when it comes time to change his diaper and sometimes you just have to deal with the screaming, fighting etc and get the diaper change over with.
Your toddler may be throwing the tantrum and hating diaper changes because he hates being interrupted when he's playing or doing something else.
Try giving him at least 30 minutes of warning that it will be time to change his diaper and then remind him every 10 minutes until it's time to change his diaper.
Then just change his diaper right where he is and then allow him to get back to playing or doing whatever it is he was doing.
Or maybe he hates being changed in front of others so maybe try taking him into a bedroom or something where he has some privacy when you're changing his diaper.
Other times he just may plain hate having his diaper changed and sometimes all you have to or can do is just fight with him.
Tell him that he has to have his diaper changed or if he doesn't like diapers he will have to use the toilet.
But even though he's resisting diaper changes it doesn't mean he's ready to potty train.