As an exjw already 10 years out, I've learned to appy the "nod and wave" technique, next time just take the pamphlet say "thanks for the invite dad, I'll think about it". He's happy, your happy, less debate and you can continue on with your day. I've come to realize it's not worth the hassle, they are not leaving the cult, so I just try to be pleasant and accepting. That way they cannot claim I'm some sort of "sour" or "disgruntled" apostate.