What are the excuses people have given to justify these atrocities?
Asalaamu Alaikum,
From an Islamic point of view there is none. In truth, the Muslim nations are weak (economy, military) and are afraid of putting themselves in the line of fire to help Muslims. For this reason, no matter what Israel does, no Muslim nation is ever going to actually do something about it, they'll simply watch.
It is a case of love for the Dunya that enables us to tolerate contradicting our own Islamic principles. Maybe this is the reason why Allah(swt) put the Muslims in the state that we are in today. Maybe we're never to come out of this state until a Muslim nation for once decides to put their self interests aside, put faith in Allah(swt) and do the unthinkable.
Allah(swt) knows best. It's just, many Muslims are under the impression that we're weak now, but wait till we gain strength, power and money "like the olden days". But they don't realise that we're not going to regain anything if all we do is "wait". The Sahabah(ra) went out of Arabia and conquered the two power houses of their time, despite knowing how the odds were against them and that they are putting themselves in the line of fire (in fact, it was worst, because they knew that they would be given no choice, and that losing would mean their women are raped, children enslaved, men executed/tortured and so on). However, their imaan was extremely high, they had love only for the Ahkirah and for this reason, would go to battle against anyone with the belief that they could win with Allah(swt)'s support. In fact, as it is reflected in Umar(ra)'s letter to Sa'd(ra) - the early history of Islamic battles always had the Muslims outnumbered, less experienced and less militarily advanced - yet, somehow - victory was attained each time. Even Historians are baffled as to how this came to be;
"The Arab conquests of the Seventh to Eighth Centuries AD, present one of the most interesting and perplexing problems of history. Their speed and performance, the immense size of the lands they covered, and most of all, the contrast between the methods used and the results produced have always been a source of wonder to historians, and it has taxed all their powers to find adequate explanation of them. The conquests have been described so frequently that they might seem a straightforward commonplace event, and yet some inexplicable and mysterious quality still underlies them. We see a horde of nomads with no military experience beyond that of desert skirmishes and bandit raids, who, at a given moment, embark on a phase of rapid expansion, confront and defeat the regular armies of great empires, advance irresistibly for thousands of miles from their native land and establish lasting control over the territories they have conquered." (Gabrieli, F. (1968) Muhammad and the Conquests of Islam, pg 103. Italian Trans. V. Luling & R. Linell, World Univ Library. NY, McGraw-Hill.)
"…Muslim forces went on to campaigns of conquest that in less than a century created an empire extending from Spain to central Asia. How all this occurred and why it focussed on Muhammad, Makkah and the late sixth century are questions that Muslims took up themselves, and that have comprised a major concern of modern historical research" (Lawrence. I. Conrad, The Arabs, The Cambridge Ancient History, 2006, vol 14, p. 695).
"The speed with which the eastern provinces of the Byzantine Empire succumbed to the Arabs remains to be explained by historians." (Andrew Louth, The Byzantine Empire in the seventh century, The New Cambridge Medieval History, 2005, vol 1, p. 298).
The result of that is known, both Persia and Byzantine fell, along with that, the conquest of Spain and Jerusalem and many other parts of the world.
But today, people don't have that kind of faith. They believe based on their worldly logic that they will lose, and that nothing will be gained. Until this mentality doesn't change, people will always have excuses to justify atrocities against the Ummah.
