All particles possess a bit of inner life, even atoms are conscious. Reductive Materialism resembles animists, but consciousness is purely mechanical property that we lack the tools to measure. Mind is the fundamental substance of the world. Experience is mental in character. The existence of inner experience is undeniable, but to an idealist the existence of an external world is not certain.
World looks like a dream state.
Idealism suggests - developing a wholly mental science based on manipulation and observation of states of consciousness, rather than states of matter. Posits the existence of a single substance possessing both mental and physical attributes. The body is seen as inferior to the soul, even down right evil. Materialism is part of the scientific enterprise. Atheistic materialism is an active unbelief in God, soul, and afterlife.