All things work together
Rather Paul is using this phrase ‘all things’ in the same way he uses it throughout his writings, as a summary statement to capture the essence of what he has just said. So if we are going to understand what he is saying here, we have to apply the ‘all things’, not to a universal sense of all things, but to the ‘all things’ that he has just described.
Obviously what the apostle has in view is the infirmities and the sufferings of the people of God. These sufferings that we endure in this world are not worthy to be compared with the glory that God has laid up for us in the future. These present sufferings are the ‘things’ that Paul has in mind. They are actually in a sense blessings in disguise, because the sufferings in this world are used by God for our ultimate good and for our ultimate benefit.
The second thing we need to note is that there is a restriction here. God is not promising to bring goodness out of all suffering for everybody. Rather he says, that in all things God works for the good of those who love him (verse 28b). It is not in the final analysis a matter of mental assent but of affection for God. Obedience, discipleship and living the Christian life are a consequence of loving God. If you love me, Jesus said, keep my commandments (John 14:15). Our obedience is based upon a prior love. The love of God is the motivating force for living a Christian life. It is not the desire to merit one’s own salvation, nor even an altruistic beneficent attitude towards our fellow men. The ultimate motivator for Christian service, Christian ministry and Christian obedience, is a personal affection for God.
The third aspect of this verse to be noted is a second distinction that makes it a passage of particular rather than universal application: who have been called according to his purpose (verse 28c). When the Bible speaks of God’s call, it never means simply the external call whereby the invitation to fellowship with God is given. Those who are called by God experience, what we call in theology, effectual calling (see comments on 1:1).
The last clause does not refer to a different group from the clause preceding. All those whom God calls according to his purpose love him, and all those who love God have been called according to his purpose.