What is the potential Paul's prayer says we can enter into?

The potential comes in response to the Apostle's prayer: to enter into a fourth dimension—to know the love of Christ that goes beyond knowledge and to be filled with all the fullness of God. This surpasses human education and technological knowledge; knowing Christ Himself is far better.

Les explains that believers now have the potential, in response to the prayer of this Apostle, to enter into a fourth dimension. Verse 19 speaks of knowing the love of Christ, which goes beyond knowledge, and being filled with all the fullness of God. Les contrasts this with the modern explosion of knowledge and technology, saying that knowing Christ is far better because it is beyond human knowledge. He also illustrates with Dwight L. Moody, who read a dying man of God's quote about hoping to be used fully and said he hoped to be that man.

Ephesians 3:19

And to know the love of Christ, which passeth knowledge, that ye might be filled with all the fulness of God.

What is the fourth dimension that Paul prayed believers would enter into?

The fourth dimension is knowing the love of Christ that goes beyond human knowledge, being filled with all the fullness of God. Paul prayed that believers would enter this spiritual dimension, which exceeds education and intellectual knowledge, so that they might know Christ in a way beyond mere human understanding.