The Greek background of the Philistines is irrelevant as the Philistines had already settled the area before the first arrival of the Israelites under the leadership of Terah, the father of Abraham. Also, it would appear that you are going with scripture. While I agree that going by religious scriptures, the lands were granted to the Israelites by God in a covenant, in Christian and Islamic scriptures it is said that the Israelites broke the covenant and hence the lands were taken away from them (murdering Prophets, I believe, was against the terms of the covenant and while Islamic scripture states that Jesus was not murdered and was instead taken to heaven, there were other Prophets who were slain. References: From the Bible; Jeremiah 2: 29 - 30, Nehemiah 9: 26, Matthew 23: 31 - 36, Matthew 23: 37, Well known Prophets slain by the Israelites mentioned in the Bible include Zechariah, John the Baptist and Uriah. From the Quran: Al-Baqarah 2: 87). So yes, from the looks of it, God did take the promised land away, if you think this is just a Christian or Muslim tradition, ask some Orthodox Jewish scholars.
Also, saying that the state of Israel has a right to Canaan based on religious scripture (which presumably entails the right to create an aparthied state and kill civilians) is exactly the same as what extremist Islamic factions claim, that they are fulfilling a covenant placed upon them by God to bring Islam to all corners of the world (even if it entails creating aparthied states where the 'non-believers' are second class citizens and killing civilians). Just waving your hands to dismiss the similarities won't do, explain exactly how one group is classified as a bunch of lunatic terrorists (I have no qualms agreeing with this notion) while the other can claim the moral high ground, both groups are going by interpretations of scripture they believe in and committing the same atrocities against humanity.