As for having same religion, same language, etc. -- well, you can say the same of Canada and the US: Except for francophone Québec, Canada and the US have similar cultures, they're both Protestant, English-speaking countries, with a history of British settlement. So why doesn't Canada just relinquish its sovereignty and become one with the US, like you say Gaza should do with Egypt? Why doesn't Guatemala become one with Mexico, whether Guatemalans want it or not? And Colombia and Venezuela, why don't we force them to become one? And Peru and Bolivia? and Argentina and Uruguay?
You see, the argument that you use to deny Palestinians their right to self-determination, can be applied against many other countries, including all those in the Arabian peninsula. Are you willing to defend this argument until its last consequences, or only in so far as it affects Palestinians?