I can answer that question in only one sentence. Well, it’s not really my answer. I find it in the Apostle Paul’s Letter to the Ephesians. However, the sentence is a long one as it begins in 1:3 and goes through v. 14. Most English translations will break this into smaller sentences since English does not bear the weight of the original well.
Not only is this a very complex sentence, the content is some of the richest in the entire Bible. The text (1:3-15) takes the form of a synagogue blessing. Paul begins this letter with a call to worship that blesses God for blessing us with all spiritual blessings.
In what follows some of those blessing are enumerated with potent verbs: God chose us (v. 4); he predestined us (v. 5); and he freely gave or bestowed his grace on us (v. 6) because of Jesus.
But more so, he chose us with particular outcomes in mind: he chose us to be holy and blameless and he predestined us to be adopted as his children. In other words, God has called us into a certain kind of life, a different way of living, that is, to live like God would live.
Paul further describes in 1:7-11 what it means to have God’s grace poured on us. Thus we have what the Bible calls “redemption.” This means that the world no longer has a claim on us, God has “bought us back” so we now belong to him to live out his purpose.
Furthermore, we now know that our sins, faults, and trespasses are forgiven because of God’s rich grace. Yet, Paul pushes us beyond an individualistic reading of the text; he forces us beyond the capacity of human imagination. As believers in Jesus, we now have an inside track on what God is up to. God’s plan includes the entire universe, not just individual humans. It involves pulling the broken universe (whether in heaven or earth) back together again (see v. 10). Paul is insistent that it is because of Jesus that all of this is possible.
Thus, in this context of God’s cosmic plan, we are “heirs” invited to participate in reclaiming the world for all that is good and right. We can be sure we are heirs because God has given us the symbol of the future. The Holy Spirit “seals us” or marks us as heirs, as those who belong especially to God.
While this passage is a long and winding text, the point is simple: God had a plan, Jesus made it possible, and the Holy Spirit guarantees it . . . and . . . as believers in Jesus we are not only a part of God’s mission but participants in it.