Why did Jesus have to be rejected like Joseph in order to bring salvation?
Jesus had to be rejected like Joseph because it was part of God's sovereign plan of salvation: through that rejection He could die for us and extend salvation by grace. Joseph's rejection preserved life in Egypt, illustrating how God uses rejection to bring about deliverance and preserve a posterity.
Les teaches that Joseph's brethren hated and rejected him and put him to death so far as they were concerned, and he ended up in Egypt. This pattern shows that the Lord Jesus Himself had to go through all of these rejections in order to bring about the whole plan of salvation, so that He could die for us and extend salvation by grace. Joseph told his brothers that God sent him before them to preserve a posterity in the earth and to save their lives by great deliverance. Les emphasizes that God is sovereign in everything He does, and the life of Joseph beautifully lays out this truth.