If God sovereignly chooses to only save some people, then is God unjust? Paul tackles this most important and practical question in Romans 9:14-29

Resources:

Romans 9:14-29

Romans by Doug Moo

Romans 9:14-29 (5 sermons by John Piper)

The Justification of God by John Piper

Systematic Theology by Wayne Grudem (Chapter 32)