1. What are the positives and pitfalls of Panentheism?
This is basically my belief so that's a positive
The positive can be not being trapped by the vision of God as an old man on a cloud but being able to see the divine everywhere visible, in everything and beyond everything. So this frees people to seek the divine in whatever way is most helpful.
A pitfall could be lack of focus - to be too easily trapped by a superficial belief rather than choosing and following a helpful path to realizing the divine.
2. What are the positives and pitfalls of Atheism?
The positive part of atheism is to insist on proof rather than swallowing a belief unexamined.
The pitfall is to insist that the proof be comprehensible by the rational intellect rather than being able to see that the intellect is not the highest form of "intelligence".
3. What are the positives and pitfalls of Spiritualism?
By spiritualism, I assume you mean communication with bodyless spirits possibly including astral travel.
I don't actually see a positive to this outside of perhaps convincing someone that the gross physical plane is not the only one.
The pitfall is that the ones contacted might be mischievous or more negative and mislead people.