The devil and sinful men can make you sick, can steal your car, can sow seeds of strife in your marriage, can take away your job, and rob you of your child. But verse 28 says, God works all those things together for your good if you love him. And if they finally work for your good, the designs of the adversary are thwarted and his aim to be against you is turned into a Christ-exalting, soul-sanctifying, faith-deepening, painful benefit. If God is for you, he does not spare you these things. But he designs good where the adversary designs evil (Genesis 50:20; 45:7). The things that are against you he designs to be for you. No one can be successfully against you.
John Piper, "God Did Not Spare His Own Son," Romans 8:28-32, August 18, 2002