13 In Him you also trusted, after you heard the word of truth, the gospel of your salvation; in whom also, having believed, you were sealed with the Holy Spirit of promise,
The first half of chapter one magnifies the spiritual wealth we have by being “in Christ,” by our status before God as equal to that of Christ.
in whom [Christ] also,
It takes belief in Jesus to be sealed with the Holy Spirit. Hearing is not enough; it requires belief in what is heard.
The sealing of the believer takes place at the point of belief in Jesus as the redeemer. This sealing is coincident with having believed (Greek grammar). Believing and sealing occur at the same time; they are two sides of the same incident. There is a vital link between believing and receiving the Holy Spirit. Sealing of the Holy Spirit is not subsequent to salvation; rather, the Christian receives the Holy Spirit at the point he believes.
Believers are spiritual millionaires and have no right to live like paupers.
Not only must we hear the word of truth, but we must act on it; we must believe it. We must appropriate all that God has done for us. There is a story of a man who purchased his own food to cross the Atlantic on a ship. It was not until the end of his journey that people told him that his ticket included all meals for the journey. Christians are like that. They do not know their spiritual wealth God has already provided for them in Christ.
We have exhaustless wealth in our Lord. This truth is of such magnitude that, beginning in verse 15, Paul prayed that we would be able to take it all in. He prayed that we would be able to comprehend the first half of chapter one.
Belief of the “word of truth” is to personally apply it as truth. The gospel fundamentally changes the core of how we look at life; we believe that the gospel is the answer and that the gospel conforms to what is true.