To prepare for Sunday, read Ephesians 1:3-14. 
This is the kind of passage I could probably ask you to read and then sign off; it’s just so rich, so full of the gospel, and in some ways, so self-explanatory. But let me offer at least a few guiding thoughts as you get into it. 
Paul says that we have blessed with “every spiritual blessing in the heavenly places.” Sounds incredible, but also a little ethereal, right? What does he mean? Thankfully, he tells us; it’s sanctification, it’s adoption as God’s sons and daughters, it’s redemption, it’s the Holy Spirit in us, it’s redemption and forgiveness and grace and an incorruptible inheritance. 
How do we access all these blessings? Paul is clear in verse 4: it’s Christ. Jesus, the holy Son of God, rightly receives all the blessings we’ve just listed, and everything adjacent to them. He deserves all the benefits of sonship. We, on the other hand, don’t deserve any of this. But God does this truly incredible, miraculous thing: he unites us to Christ. We are connected to Jesus; this is what the Bible means when it says we are “in Christ.” And all of this happens simply by faith! As we heard last week from John 6, we just believe; we extend the open hand of faith to receive from God all the blessings he gives to his own Son. He never turns away any who believes, and he never withholds or withdraws any of his blessings. In Christ, we inherit every single spiritual blessing in the heavenly places.
When I think about all of that, I understand why Paul is exploding into praise at the start of this passage. What else are we supposed to do? God’s love for us us in the gospel is beautifully overwhelming. We’ll never get all the way to the bottom of it, and we can’t even begin to repay him for it. So, we just pour out our hearts and voices and lives in worship, to the praise of his glorious grace.