Reference

Exodus 29:35-37, Genesis 8:19-21, Exodus 30:7 & 34-37, John 4:23-24, Romans 12:1, 1 Peter 2:5 

In the Bible, the altar signifies a sacred meeting place between God and man:
The altar was used for: Sacrifice, Worship, and Transformation. We are called to become Living Sacrifices unto God, and our hearts become the altar.