The mass rally organized by Hamas in Gaza to celebrate its 21st anniversary yesterday was a spectacle repulsive to Israelis. With trademark cruelty, the gathering included a provocative "play" featuring a character dressed as captive IDF soldier Gilad Schalit, pleading in Hebrew for his freedom: "I miss my mom and dad." The pain deliberately caused to Schalit's parents, more than 900 days after his abduction, would have been of little concern to Hamas. As it marks its 21st birthday, Hamas pays no heed to the fact that Schalit has been denied his freedom on his 20th, 21st and 22nd birthdays. Indeed, it aims to keep picking at the open wound, hoping to build pressure from within Israel on the government to conclude the kind of staggeringly unbalanced prisoner "exchange" that Hamas is demanding - a soldier kidnapped from inside Israel's borders in return for a mass release of Palestinian security captives, including murderers. But the kind of Hamas callousness exemplified at yesterday's rally should not only be repulsive to Israelis. It should give pause to the whole world, and most especially to Hamas's co-religionists. Hamas's avowed agenda of seeking Israel's elimination, its amoral treatment of Schalit, its cynical use of Palestinian residential areas as the launching points for incessant rocket attacks on Israel, its violent overthrow of Palestinian Authority rule in Gaza - all of this is pursued, as its suicide bombing campaign has always been pursued, in the purported name of Islam. "Some may wonder, 'Just what is the spirit of Islam?'" muses a Canadian-based Web site called Spirit of Islam. It answers, succinctly, by defining the faith as "a fine balance between knowledge and action; a beautiful collage of peace, kindness, justice, honesty, integrity and respect." Not, sadly, in the Hamas definition. Nor, either, in the approach to Islam championed by Hamas's similarly vicious bigger brother in Lebanon, Hizbullah. And not by their shared state sponsor, Iran, now seeking the nuclear means to achieve its desire of Israel's elimination. Hamas purports to represent a humane Islam. One of its leaders in Gaza, Mahmoud Zahar, claimed last week that Schalit was being well-looked after because "Islam treats hostages well." But, as Zahar was forced to acknowledge, Hamas has consistently rejected requests for the Red Cross to visit Schalit, as required under international law. Hamas claims to represent a humane Islam, and yet it chose to bring suffering on its own people, in the wake of Israel's unilateral withdrawal from Gaza, by intensifying cross-border rocket fire - destroying the Palestinians' opportunity to start the process of state-building. Now Hamas is threatening to end months of Gaza-Israel "cease fire" - a relative term of increasingly little value - and thus, potentially, to spark still further futile violence. COMMENDABLY, MOST of the international community has resisted the idea of legitimizing Hamas so long as its does recognize Israel's right to exist, abandon terrorism and accept previous Israeli-Palestinian agreements. But the international community sometimes loses track of the fact that the suffering in Gaza, as Israel seeks to thwart the rocket attacks on its civilians, is a consequence of Hamas's disinclination to meet those minimal conditions. Even Israel's leaders have not always internalized the impossibility of dealing with the bleak, unyielding Hamas. But while Foreign Minister Tzipi Livni and would-be Likud defense minister Moshe Ya'alon have drawn criticism from the "free Schalit at all costs" supporters, their latest comments unfortunately make belated good sense. Kadima leader Livni told high school students in Tel Aviv last week that "we all want Gilad to come home, but there is always the risk of minimum casualties and it isn't always possible to bring everyone home." Ya'alon, a former chief of staff, asked rhetorically on Army Radio yesterday: "Are you ready to give up the State of Israel for a prisoner?" Hamas's demands are insatiable, because its opposition to Israel is absolute. An organization that shot dead its own Palestinian people when taking power in Gaza in June 2007 has no compunction in killing, kidnapping and manipulating ours. Israel can afford no illusions when it comes to confronting, marginalizing and ultimately defeating Hamas. Adherents of a very different Islam, an Islam of "peace, kindness, justice, honesty, integrity and respect," should share that ambition.