To see the altar in your dream suggests that you are making a great personal sacrifice. You may also be expressing concerns about your spirituality. The dream may also be a pun on your need to “alter” some behavior, attitude or aspect of your life.
To see a priest at the altar in your dream signifies strife and disharmony in both your work and home. The dream may also point to some guilt that you are suppressing and refusing to acknowledge.
To dream that you are kneeing in front of the altar represents unfulfilled desires.
In particular, seeing a satanic altar in your dream indicates that a dark power or energy is at work.