This means that he was baptized a Mormon, but stopped going to church somewhere along his life... Sometime after he married my mom in the Mesa Temple.
I do not remember him going to church very often with me, my mom, and my two sisters.
If I think back to when I was a child, I remember sitting by him in a sacrament meeting, passing the little sacrament cups down the row for the deacons to collect. We used to take the little paper cup of water, pass the tray, and then pass our used cup to the person next to you, so that at the end of the row the last person would have a tall stack of little cups. (kind of unsanitary in today's world--but that was a step up from the days of sharing a cup.)