Christians from the first church as well as Christians from your great-grandparents' church would be comfortable with the unchanging message that we share in our services. Our theology isn't some new, feels-good-but-lacks-substance musings based on personal ideas. It's biblical, practical, uplifting, inspiring, challenging and convicting. And it does feel good to hear about God's unconditional love for us. 

Our worship music, on the other hand, might make your grandparents a little uncomfortable. They'd be fine with the lyrical content, but the music style might be a little too contemporary for their tastes. It probably depends on your grandparents, doesn't it?