Aagaard had traveled to Asia and was concerned about Buddhism and other Eastern religions, which he felt were gaining influence in Europe.[7] In 1973, Aagaard founded the Danish Dialog Center, which was part of the Dialog Center International, which was later greatly influential in promoting a negative public opinion of cults in Denmark and other European nations. He regarded Scientology as being especially dangerous, but later in his life stated that Islam was an even greater threat. Other concerns included Satanism and New Age groups. Aagaard cooperated with both religious and secularanti-cultists, but opposed deprogramming of cult members since he felt that it was ineffective and often counterproductive. He retired from the Dialog Center in 2002.[8][9]
Mission, Konfession, Kirche: Die Problematik ihrer Integration im 19. Jahrhundert in Deutschland, Gleerup, 1967
"The First Furlough", International Review of Mission56, no. 224 (1967): 439–443
"Trends in Missiological Thinking During the Sixties", International Review of Mission62, no. 245 (1973): 8–25
Missions from the north: Nordic Missionary Council, 50 years, co-author with Carl F. Hallencreutz, Universitetsforlaget, 1974
"The Truth Which is at Both Extremes: A Reaction", International Review of Mission66, no. 261 (1977): 29–31
New religious movements in Europe, co-author with Helle Meldgaard, Aarhus University Press, 1997
Identity in conflict: classical Christian faith and religio occulta, co-author with Moti Lal Pandit, Helle Meldgaard, Mike Garde, Munshiram Manoharlal Publishers, 1998
The hidden way: a study in modern religious esoterism, co-author with Moti Lal Pandit, Munshiram Manoharlal Publishers, 2002
"Occultisme/Satanism and the Christian faith" in Le Défi Magique, Volume 2: Satanisme, Sorcellerie, edited by Jean-Baptiste Martin and Massimo Introvigne, Presses Universitaires de Lyon, 1994
