Why did nationalism in Europe become a means to instill hate?
Nationalism means to put your nation's interests above international considerations. Patriotism is taken to an extreme and devotion to your own country above all others is a virtue. In this environment, anyone or any other nation becomes an object of suspicion as they are not the favored nation. To go from suspicion to hate is a small step on the slippery slope of becoming an extreme nationalist. Hitler used this in his time to make Germans consider only Germany's interests and to hate those who opposed its goals. He appealed to German pride and to past German military glory to raise nationalism to new heights. Hitler used the loss of power after WW I to encourage and sustain hatred for nations and people who had contributed to Germany's lowly status. Thus, he could begin his campaign of hatred. In current time, countries are trying to eliminate refugees entering their country as they flee war. The words being used are nationalistic as in the keep our country free from other religions and nationalities. Fights and hatred are the result even now.