This title only occurs in this letter where Paul uses it on five different occasions. We need to consider each of them in order to see what it describes. The title could suggest that it refers to heaven, and some of the occurrences would support that idea. But other places indicate that it means more than heaven. The places where Paul uses the title are these:
1:3: Paul says that the heavenly places are where spiritual blessings are enjoyed. This description points to the meaning not being heaven because Paul says in the verse that believers already have these blessings even while they live on earth.
1:20-21: Paul writes concerning God’s power ‘that he worked in Christ when he raised him from the dead and seated him at his right hand in the heavenly places, far above all rule and authority and power and dominion, and above every name that is named, not only in this age but also in the one to come.’ This verse indicates that Jesus is the supreme authority in the heavenly places, and he was exalted to that position after his resurrection and ascension.
2:4-6: ‘But God, being rich in mercy, because of the great love with which he loved us, even when we were dead in our trespasses, made us alive together with Christ – by grace you have been saved – and raised us up with him and seated us with him in the heavenly places in Christ Jesus.’ In these verses Paul is describing the new life that believers have, an aspect of which is that they are united to Christ and share in his exalted position.
3:10: ‘so that through the church the manifold wisdom of God might now be made known to the rulers and authorities in the heavenly places.’ Paul refers here to angelic powers who live in the heavenly places, that these angels learn about God’s wisdom as they watch the people of God. It is not clear if these angels are good angels or evil angels, although I suspect it refers to good angels.
6:12: Here Paul says that believers engage in spiritual warfare with evil angels in the heavenly places: ‘For we do not wrestle against flesh and blood, but against the rulers, against the authorities, against the cosmic powers over this present darkness, against the spiritual forces of evil in the heavenly places.’
So the ‘heavenly places’ is the location where we enjoy spiritual blessings, where we live out the new life Christ gives, where angels learn about God’s wisdom, where we fight our spiritual foes, and over which Jesus reigns. What Paul means by the term ‘is the unseen world of spiritual activity’ (John Stott).
Paul calls this unseen world ‘the heavenly places’ because he is reminding Christians again that they live in two worlds simultaneously. At one level they live on an earthly plane, eating and drinking and working as everyone else. But at a more profound level they also live in a spiritual world in which they are united to Christ.
But since the heavenly places include spiritual warfare this is a reminder to us that we have to fight the powers of darkness in order to enjoy our spiritual blessings. I suspect we have an important clue here as to the nature of spiritual warfare: the devil works to prevent us appreciating what the Triune God has done for us.
A biblical example of having to fight to maintain our enjoyment of the benefits of these blessings is the children of Israel coming into Canaan under the leadership of Joshua. God had given to them all the blessings of the land as their inheritance. But there were giants there determined to prevent them and they had to destroy them in order to maintain the state of blessing. Similarly, the church has been given these blessings (note the tense), but they will have to wage spiritual war to continue enjoying them.