You also, as living stones, are built up as a spiritual house, to be a holy priesthood, to offer up spiritual sacrifices, acceptable to God through Jesus Christ.
Jesus is a cornerstone, the foundation upon which the church is built, but yet He is also a stumbling stone. The Jews stumble over Him because of the crucifixion. They could not understand the Messiah being crucified and so they stumbled over this stone. He became a rock of offence to them.