Prejudice.

It is God’s will that the differences between nations should disappear. Those who help on the cause of unity are doing God’s work.
Unity is the Divine Bounty for this luminous century.
Praise be to God, there are today many societies and many meetings held for Unity.
Enmity is not so much the cause of separation as it used to be; the cause of disunion now is mostly prejudice.

‘Abdu’l-Bahá in London