Because of the religious nature of its founder, Aikido is a martial art with a deep spiritual side.
Morihei Ueshiba was a fervent Shinto practitioner, and wanted to bring inner peace to men through Aikido.
He was also was influenced by a Shinto religious sect called Omoto Kyo, whose spiritual leader Deguichi Onasiburo preached non-violent resistance, universal disarmament and the unity of all Creation.
Aikido has a spiritual goal represented by the search of harmony within ourselves, the others and the Qi. Its principle (named Aiki) is the unity with nature, universe and mankind.
The Aikido practitioner (aikidoka) seeks to harmonize spiritually and physically with the opponent (not to overpower him) and with In and Yo (the equivalent of Chinese Yin and Yang).
Aikido follows Budo in order to improve the character of the practitioner.