Nay but, O man, who art thou that repliest against God? Shall the thing formed say to him that formed it, Why hast thou made me thus? Hath not the potter power over the clay, of the same lump to make one vessel unto honour, and another unto dishonour?
- Romans 9:20-21 (KJV)

The phrase "unto honour, and another unto dishonour" means "for special purposes and some for common use".

We don't always know why things are the way they are, but one thing is certain, and that is that we can trust God.