When the Muslims were attacked by the Christian Crusaders and were either made to convert by force or faced murder, they were justifiably angry and aroused. That is very likely why they developed a strong hate for the Church and may have marched into the lands of southern Europe in order to gain their own territory.
I believe Muslim conquests into southern Europe could have been a direct reaction to Crusades into the Holy Land. This battle between Christianity, Judaism, and Islam has been going on forever and chances are if something appears to be linked and associated with these religions, then they probably are, in my opinion.
Without a doubt, Muslim conquests into southern Europe were a direct reaction to Crusades into the Holy Land by Christians. These conquests into Europe were not necessarily justified, but the Christians did the exact same thing going the other way. Therefore, nobody should blame the Muslims for what they did.
After the Crusades, the Muslims wanted revenge for the Europeans' occupation of their lands. The Muslims retaliated by attempting to conquer southern Europe itself. It is clear that there is a major clash of ideals between the two religions, and this conflict in many ways endures even into the modern world.
First of all, do you mean Iberia or Eastern Europe. Regardless you are incorrect historically. Islamic forces reclaimed the holy lands from the Christians by the end of the series of middle eastern crusades. Even if we ignore that fact, the conquest of iberia was far before the first crusade and the conquest of eastern europe by the ottomans was merely political as opposed to religious as is evidenced by the survival of christianity in the ottoman's european territories.
No, I do not think Muslim conquests into southern Europe were a direct reaction to Crusades into the Holy Land, because they were competing separate agendas. Both of the religions wanted to advance their position through the use of force. Each one would have still attacked if the other hadn't been doing the same thing.