This comprehensive statement is limited to the things that the prophets said would be restored, which suggests that some things that were lost will not be restored. Therefore, we have first to find out what things were lost, when they were lost, and see if they are among what will be restored.
The Bible is very clear about two different groups of creatures that will not be restored. One group is the fallen angels, the ones who followed the leadership of Satan when he rebelled against God. No restoration has been offered to them. The other group is fallen human beings who remain impenitent about their sins. Many of them had salvation offered to them, but they rejected it. The long-term consequence of their choice is that they will not take part in the restitution of all things.
The answer that the Bible gives to this most important question is that all things in the creation of God were damaged or spoiled at the beginning of human history through the decision of Adam to disobey God and listen to the ruler of the kingdom of darkness instead. We know that the credibility of an answer is that it explains the situation. The curse that came upon the creation explains the existence of physical troubles such as earthquakes, famines, and other natural disasters. They are reminders to us that we live in a world that is under the judgement of God.
This world has many pleasant features and these are all the results of God’s common grace. We can think of the advances in science, the abilities that musicians and artists have to create beautiful music and paintings, the stability of authorities such as human governments, the security of family life. There are many other blessings connected to life in this imperfect world. Nevertheless, we know that these features can also become means of destruction whether it be spiritual, moral or physical destruction. Over every feature of life can be written defilement, danger and death. Scientists produce weapons of war as well as tools for curing people; musicians and artists create music and art that breeds despair instead of joy; governments can be guilty of oppression; even families can be places of spiritual danger. Despite the attempts of philosophers to give education, of philanthropists to create better conditions, and of politicians to create just societies, something always goes wrong. The reason that explains all the evidence is that this world is not as it should be, that God has placed a curse on life in this fallen world.
Of course, to have only this assessment would not give us much hope. Thankfully the Bible informs us that there will yet be a better world, a perfect world. This statement by Peter here in Acts 3:21 is one of several biblical passages that describe for us the future of this cursed and defiled universe. He elsewhere says: ‘But according to his promise we are waiting for new heavens and a new earth in which righteousness dwells’ (2 Pet. 3:13).
The clearest description is given by Paul in Romans 8:18-22: ‘For I consider that the sufferings of this present time are not worth comparing with the glory that is to be revealed to us. For the creation waits with eager longing for the revealing of the sons of God. For the creation was subjected to futility, not willingly, but because of him who subjected it, in hope that the creation itself will be set free from its bondage to decay and obtain the freedom of the glory of the children of God. For we know that the whole creation has been groaning together in the pains of childbirth until now.’
In a way that we cannot possibly understand at present, the universe is going to be liberated from its bondage to the curse. This great event will occur when Jesus returns. There is a wonderful picture of this great event in Revelation 21:5-7: ‘And he who was seated on the throne said, “Behold, I am making all things new.” Also he said, “Write this down, for these words are trustworthy and true.” And he said to me, “It is done! I am the Alpha and the Omega, the beginning and the end. To the thirsty I will give from the spring of the water of life without payment. The one who conquers will have this heritage, and I will be his God and he will be my son.” Jesus, the Heir of all things, will provide the restored universe as the inheritance of his brothers and sisters for ever.