Show factual proof of this "spirit" you speak of and I'll be right beside you in your conversation.
You are not going to walk any intelligent person into your conversation starting with "spirits" are any more real than the myths in the bibles.
What will you accept as fact? The reason I ask is that most atheists want physical, objective proof of a spiritual being. They want a lab-type of experiment where under the same conditions, one can see the same result being produced time and again. This happens because all variables (but one) can be controlled.
A physical change can be traced to one object acting upon another object. Let's take a tree growing near a stone fence. One day the fence topples over. The result: The roots growing under the fence, moving it until once alignment is sufficiently lost, the fence topples. This might take years. The tree roots didn't suddenly grab the fence and pull it down.
Spiritual growth (or devolving) can be shown to work in much the same way. A person doesn't usually change in an instant, but over time change is noticed. Working backwards, this can oftentimes be traced back to a profound spiritual experience. Love enters a life--or love emerges from within--and it makes a difference.
One of the better reasonings for spirit is that a brain can present alternatives, but is it the brain that chooses, or is it the person within that tells the brain which choice to invoke? Where does this spirit come from? Physical matter can be shown to come from physical matter. Likewise, it seems reasonable that spiritual matter comes from spiritual matter. In other words, there is both a physical realm and a spiritual realm. Humans are not just mind and body, but spirit, mind, and body. Wouldn't mind and body pretty much be robotics--and we humans are not robotic.
Still, my purpose is not to convince you there is a God. My only thought is to perhaps redirect notions of where God may be found. The reason God "fails" so many atheist tests is because these tests try to pit spiritual power against physical objectives. That would be like trying to improve someone's spiritual (or moral) health by having him/her eat broccoli.
My atheist husband wants a God who can help him move literal mountains in this physical world--instantly. He's not too interested in a God who helps us move non-literal mountains in our lives--and usually takes a long period of time to help us accomplish it. Also, it usually requires some sacrifice on our part as even non-literal mountains don't move easily. He's not that interested in sacrifice, either.
Atheists who truly wish to understand people of faith will try to understand we are not people of faith because someone talked to a burning bush; or someone survived a flood; or someone walked on water. What keeps our faith steady is what happens privately, in our innermost being. That is often something too intimate and precious to share with known atheist scoffers--but not with atheists who also value intelligence and reason.
Sorry this is so long. I need to practice brevity.