Complex sentence: Eventually, the Ancients decided to build a space ship and leave rather than to use their technology like the Ark of Truth to defeat the Ori,, mainly because they thought it to be philosophically and morally wrong.
Split into simpler sentences: Eventually, the Ancients decided to build a space ship and leave rather than to use their technology, like the Ark of Truth to defeat the Ori. Though they had the ability to stop the Ori, they thought it to be philosophically and morally wrong.