You obviously spent those days watching Pat Robertson because CBN was literally the only ad free channel on cable that anybody actually watched in the earlier days. And as far as I know, it's still ad free.
CBN operated from 1977 through 1997, showing ads starting in 1981 and taking the name The Family Channel in 1988. Beginning in 1997, CBN was reduced to a paid programming arrangement to show The 700 Club on what is now Disney's Freeform channel. There are, however, numerous other religious channels under a viewer donation arrangement like what you describe, such as EWTN. And in 2008, CBN started a second channel called CBN News, first online and then with a handful of broadcast affiliates.