A Phrase Well Known, this phrase stand as the asking of freedom for the people in Gaza...or does it? Let's ask a few question and slowly yet surely get to an honest conclusion about this phrase.
Question 1:What is the River refered to in this quote?
Considering the major sea in the middle east and the only one connected to Isreal or Gaza being the middle sea, we can assume that this is the sea implied in the quote. However, if the middle sea is one border of "Palestine", that "River" must be the other. However there are no notable and certainly not border-like rivers in the state of Gaza
The nearest option for a big "border" river is the jordan river.
Question 2:What does "Palestine" means in this quote?
Since "From river to sea" implies the boundaries of "Palestine", we can infer that "Palestine" actually refers to the State of isreal, as it's borded by the middle sea in the west and by the Jordan river at the east.
Question 3:If "Palestine" equals to the State of Isreal, What does "Free Palestine" implys?
The state of isreal is not under any lock and key, unlike Gaza, and therefore the notion of "Rebillion for locking us" for the freedom of "Palestine" doesn't work here.
The other likely implcation of "Free Palestine" means taking control over it, I.E taking control over The state of Isreal.
Conclusion
So from this path of reasoning we now got a more concerte meaning for the quote:"From the Jorden River to the Middle Sea, the state of Isreal will be freed from it's people and be ours again."
Therefore, supporting this quote most likely implys you are consent with the Palestines taking over the state of Isreal and dooming millions, not even just Jewish or Israeli to be left to their own devices, or even executed.
In other words, you support a second holocaust for people of Isreal.