I have read parts of the charter previously, and clearly, it's not pleasant.
I am not a supporter of Hamas in any way, but I don't think that what they want for now to stop the current violence is unreasonable.
Anyway, this is going off topic, so back to the point.
The necessity for a state such as Israel is still only opinion, not fact. As you say, we can have opinions without them being fact.
I am obviously not going to argue that there was no need to do anything to aid the Jewish people after WW2, it's more than obvious that something needed to be done for them, but I disagree that creating Isreal in the way that it was created, was the only solution.
It was one option, and considering what has happened to Palestinians since it was created, I think it's reasonable to consider that it might not have been the best option.
What I disagreed with was this
If you deny the right of Israel to exist, then I'm afraid, you are anti-Semitic
It doesn't make sense to say that if you don't agree with the politics of a situation then you are automatically racist. It's just not that simple.
Being racist is to judge someone negatively because of the country they were born in, or because of the colour of their or skin, or because they are from another race.
Being racist is not disagreeing with the way a country was set up, especially when the setting up of that country led to horrendous suffering for people (who are incidentally also from a different race to your own).