a group of 15 men were arrested on suspicion of ` multiple aggravated murder motivated by religious hate ' .
last week after 12 christians from ghana and nigeria were allegedly thrown off a rubber dinghy into the mediterranean sea .
survivors from the boat , made up of 105 migrants from diverse religions and ethnicities , have now claimed the men tried to throw other christians off the side of the vessel after an argument about religion - but were prevented because they huddled together to create a human chain .