Don't be too sure, though I doubt you're making a stern declaration above.
I myself communicate both ways with a former mentor and spiritual advisor who passed from this plane about eight and half years ago.
I suppose that means I could do it with others as well, but I've yet to give it much of a go.
There are countless stories from people with great integrity who have had or continue to have ongoing contact with close loved ones who have made the transition from this plane.
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Many of the more zealot Fundamentalist sects of Christianity discourage the exploration of these type of communications - suggesting that it can be dangerous and expose the inquiring mind to some type of demonic or satanic invasion. Make of that what you will. I'm sure it's little surprise I find such notions rather silly.