This is a different game from Mega Tensei Gaiden: Last Bible Special, which released afterwards and took place during biblical times. Instead, Last Bible takes place in the middle ages.
The game has an official English release for the Game Boy Color in North America, but the Game Gear version never made it Westwards. The Game Gear version added an expanded story, revised events, and two possible endings to complete.
With this game now translated, the entire Last Bible subseries of Megami Tensei games have now all gotten translated or fan-translated in some manner. You can find a link to the patch here.
Megami Tensei Gaiden: Last Bible was released for Game Boy Color and Game Gear in 1992 and 1994 respectively in Japan.