''He's one of the most fascinating characters I've ever studied,'' says Christian Bale of Moses, the Old Testament prophet he plays in Exodus: Gods and Kings. ''All of his trials, his troubled life and his doubts, his rages and his extremes.'' Exodus aims to present a more rounded portrait of the man many know only from Sunday school. That process began with director Ridley Scott. ''As a filmmaker I'm always attracted by who the central character is and what they face,'' says Scott, who calls Moses' life one of the greatest adventures and spiritual experiences of all time. ''I was knocked out by who he was...and the actual basics of the story.'' Scott also knew that Bale, with whom he was friendly but had never worked, would be perfect for the role. Says the director, ''I wanted to save something special for him.''