Your understanding of history is flawed. By the time Western powers began adopting the separation of church and state, they were already dominant around the world.
The United States was one of the first western powers to create a government based on secular enlightenment ideals. However the United States was created in 1783. By this time the Spanish, Portuguese, British, Dutch, and French empires already had colonies around the world. The wars they waged (such as the Seven Years War) had fronts ranging from India to Canada.
The Great Divergence is considered to be the point when Western civilization began surpassing other world civilizations. It began around the 15th and 16th centuries (during which time the Catholic Church was still supremely influential). The causes of this divergence were the Age of Exploration and the invention of capitalism and industrialism as a result of the resource influx from new colonies.
en.wikipedia.org
No, defeating AS isn't that difficult. All you need is a competent government. If the Somali government was at least as competent as your average African government, AS would be defeated by the end of Ramadan. This episode highlighted the SNA's incompetence as they didn't even take the most basic defense measures in their bases.
Of course you, me, and everyone else on this forum already knows this. You simply saw this as another opportunity to engage in your anti-Islam trolling.