A number of Western countries have been urged to integrate Sharia law (Islamic religious law) into their legal system by their Islamic residents. The idea has even found some favour amongst some of the leading and influential people, such as politicians and church leaders, in those countries.
Islamic fundamentalists, and also many moderate Moslems, have realised that their goal of Islamic rule of the world, as Islam dictates that they should, achieved by armed conflict would be extremely difficult and would have some undesirable results. They have realised that outright war would be as destructive to them as to the country they were attacking. Instead, they now aim to attack the basis of Western society; its legal system. If they can destroy a country's legal system they will destroy the country in a bloodless victory for Islam. The integration of Sharia law into the country's legal system is the first step on that road to conquest and domination.
To be fair to everyone, if Sharia law were integrated into a country's legal system, then other religious (taking 'religious' in its broadest sense) groups must be granted the same privilege, or else they could cry "Discrimination!". So we would see integration of Jewish law, Buddhist law, Hindu law,.... And what about Aboriginal law in Australia and Native American law in the US? They must be included also. Satanic law? It's a religious view so it must also be included. And so on and so on .... The result would be a legal maze of laws and precedents that would please the heart of any lawyer wishing to gain his/her client's freedom.
Consider: A person is charged with some crime. Amongst the maze of laws and precedents her/his lawyer would surely find something to get the charge quashed and the trial abandoned. The person would go free. The time and effort of the Police in gathering evidence and the courts in trying the case would be wasted. Crime would go unpunished.
But it gets worse. If a charge could never be made to stick, then the Police would no longer have the function of gathering evidence for a trial and would become redundant. Their role of enforcing the law would become impossible due to its extreme complexity. With no evidence or information available for a trial, lawyers, judges and the whole legal system would no longer be required. With no convictions happening there would be no need for prisons. The whole legal, judicial, penal system would no longer have a function and would stagnate and collapse.
The criminal fraternity would love that! Except that they would no longer be criminals under the new laws. And they wouldn't be happy for long.
The result would be truly anarchy - that is no (effective) law, due, in this case, to an overabundance of law that was useless and ineffective and could no longer function to stop crime nor protect ordinary citizens. The effect would not end there. With no functioning legal system the country could no longer function. It, too, would collapse into disarray.
Since the same situation would have been happening in a number of countries at the same time, none of them would be able to come to the aid of their neighbour. The countries would collapse like a row of dominos. The fall of the West would be imminent and unavoidable.