Resistible or Irresistible?

I was given a question to ponder this week, by one of the leaders in my church.

"Is the Spirit moving around you resistible or irresistible grace?"

I've been pondering this question and having trouble a bit. Tom said he posed the question to me because he knows I "go home and think". I naturally am inclined to say resistible because of free will, but once I personally noticed the Spirit moving in my life, it was irresistible. I'm still pondering this question that bloggles the mind!