You're already in error to ask for support for positions based on the Bible, because the Church determines the Bible's meaning, not the other way around. If you're evaluating claims against what you think the Bible means, your religion is based on yourself, not on God's Church, and you are a heretic and stand condemned.

The reasons for Christ's death are deeper matters to discuss with those in the Church. The Church is responsible for salvation because it was ordained by God through Christ to be His physical manifestation in the world; there is no other way to Him.