The venerable Catholic priest of blessed memory, Fr. John Hardon, S.J., says it is, and he explains why:
Yoga is incompatible with Catholicism because the best known practice of Hindu spirituality is Yoga. “Inner” Hinduism professes pantheism, which denies that there is only one infinite Being who created the world out of nothing. This pantheistic Hinduism says to the multitude of uncultured believers who follow the ways of the gods that they will receive the reward of the gods. They will have brief tastes of heaven between successive rebirths on earth. But they will never be delivered from the “wheel of existence” with its illusory lives and deaths until they realize that only “God” exists and all else is illusion (Maya). To achieve this liberation the principal way is by means of concentration and self control (yoga).
Indian spirituality is perhaps best known by the practice of yoga, derived from the root yuj to unite or yoke, which in context means union with the Absolute. Numerous stages are distinguished in the upward progress toward the supreme end of identification: by means of knowledge with the deity; the practice of moral virtues and observance of ethical rules; bodily postures; control of internal and external senses; concentration of memory and meditation–finally terminating in total absorption (samadhi), “when the seer stands in his own nature" . . . (continue reading)