Ephesians 3:16 that according to the riches of his glory he may grant you to be strengthened with power through his Spirit in your inner being,

Paul prays for the Ephesians in order for this to happen.

Ephesians 3:17-19 (English Standard Version)

 so that Christ may dwell in your hearts through faith—that you, being rooted and grounded in love, may have strength to comprehend with all the saints what is the breadth and length and height and depth, and to know the love of Christ that surpasses knowledge, that you may be filled with all the fullness of God.

May dwell is not a guarantee. Paul knows God’s will is paramount. This gospel only lights the path, we still have to walk in it by faith.

1 John 5:4 For everyone who has been born of God overcomes the world. And this is the victory that has overcome the world—our faith.