You are quite right. The word Irresistible, is never used in the BIBLE.
In fact the ONLY place I could even find it was the NIV bible and they use it, as a MADE UP ADJECTIVE, which is not in the GREEK, talking about a Great Mighty Army sweeping over everything like a flood.
Daniel 11:10 (NIV)
10 His sons will prepare for war and assemble a great army, which will sweep on like an irresistible flood and carry the battle as far as his fortress.
The NIV clearly made that word up. I suspect that she is talking about the "Charismatic Experience", which some assume it is the Holy Spirit. If that is what she wants to believe, I guess she can do that if she wants to, as long as it is in a Charismatic or Pentecostal Church. Personally in my opinion, it is all counterfeit, but that is just my opinion, and it is not my understanding.