If it is true that human beings will worship something, then the question of true worship is clearly very important. How are we to keep ourselves from idolatry, giving the kind of honour and respect which we call 'adoration' to the living and true God and to Him alone?
The wonderful first reading from the Book of Leviticus spells out the times and kinds of worship that were pleasing to the Lord, the God of Israel. These were times for renewing the covenant and for returning to life within the covenant. The rituals described combined seasonal feasts, found in many cultures, with historical anniversaries, also found in most cultures. No reason is given for the particular arrangement of times, seasons and actions beyond 'I am the Lord'. It was the Lord's will that he be worshipped in these ways and that his actions on behalf of the people should be recalled in these ways.
Anthropologists will find reasons appropriate to their discipline in this list of feasts and festivals - one need refer only to the work of Mary Douglas to see how rich a mine Leviticus is for anthropological study. But theologians see 'worship' in all of this, the ways in which the Mosaic Law laid it down that God was to be honoured and respected, the covenant observed and renewed, breaches of the covenant confessed and forgiven. It is a complex ritual system designed simply to acknowledge God's glory. To borrow a phrase from the Jesuits, whose founder Saint Ignatius we remember today, it is all 'ad majorem Dei gloriam', for the greater glory of God.
In fact the Spiritual Exercises composed by Saint Ignatius can seem like a modern Book of Leviticus, a complex system not so much of rituals as of personal introspection and meditation designed, like the public worship of the Israelites, simply to acknowledge God's glory. The Exercises, is a modern work, belonging to a time when a new emphasis on the individual was emerging, and focused on the acknowledgement of God's glory in the life of the individual Christian. The Book of Leviticus was focused on the community of believers acting together in common praise and worship of God, a liturgical spirituality in the literal sense (liturgy = a work of the people).
Both Leviticus and the Spiritual Exercises are directed to Christ, his sacrifice and the ways in which we share in it. Leviticus anticipates Christ and the Exercises are designed to lead people to Christ. We know, what was not yet known to the people of Nazareth when he returned there, that in Jesus all the sacrifices, rituals and festivals of the Law were brought to an unexpected fulfillment. On one level the people of Nazareth knew more about him than we do: who his father, his mother, and his brothers were. But on another level we know more about him - that in his body he fulfills all the divine promises made to Israel just as in the same body he offers perfect worship to the Heavenly Father. Our liturgical and spiritual exercises enable us to share in that fulfillment as they enable us to participate in that worship.