When I was in middle school, a gold chain worn around the neck was a prized possession. Like most kids, I wanted to fit in and be accepted, so I petitioned my mother for a new golden chain. She kindly obliged and took me to one of the finest “knock-off” jewelry stores in town! And for a steal of a deal, I purchased one fine golden chain in exchange for one crisp Andrew Jackson.
For those: This refers to the Church,--those in the second Adam (Jesus).
Whom he foreknew: This word foreknew can also be interpreted as fore-loved. For those whom God loved before the creation of the world. God loves his creation, but he loves his new creation in a greater, more intimate, and salvific way.
And through this love he also predestined the Church to be conformed to the image of his son. Before man could even act out in disobedience, God set aside a group of people to bear the image of his son. Then Christ came, as the firstborn among many brothers, to secure this group of people through his life, death, and resurrection.
The chain continues as those whom he predestined he called with an effectual calling. This is a saving call as that of Lydia in Acts 16:14.
Those whom he called he also justified. We are justified when God takes our guilt away and bestows upon us the righteousness of Christ (2 Corinthians 5:21).