First, be reconciled to your brother, then come and offer your gift.--Matthew 5:23-24
I have meditating on these words from Jesus a lot over the past week or so. I think a part of what Jesus was telling his disciples was that, more important than the activities of the church, or temple worship, or sacrifice, or tithing, were people. Jesus was telling his hearers that it is relationships that really matter. The whole Bible is about relationship--God with us, and us with one another.
Relationships are messy. Broken people loving broken people. Forgiveness and reconciliation need to be a part of the fabric of what marks us as Christians. It will likely be required of us often (In Matthew 18, Jesus mentioned something about 7x70 times). Yet, more than any other act of worship that we may be involved in--singing, tithing, service--Christ calls us to relationship.