Blessed be the God and Father of our Lord Jesus Christ, who has blessed us with every spiritual blessing in the heavenly places in Christ... (Ephesians 1:3).
Familiar as these words and these thoughts are to us, there are tremendous possibilities of freshness, and newness, about the enjoyment of these things... If there is no fresh glimmer of light and glory associated with the reiteration of this truth, there is all the more reason why we should ask the Lord what has happened to us, that we could contemplate such a thing without a stirring of heart. Now, is that our Christ, the Christ of our experience, the Christ of our knowledge? Are we living in the realisation of that, not to its fulness - because that fulness will never be exhausted - but in the wonder of the fulness which lies before? - a land flowing with milk and honey, a good land indeed. Any fresh contemplation of our Lord in this way should ravish our hearts: Christ, the fulness of spiritual blessing now, the Sphere of our experience, our exploring, our enjoyment, our satisfaction. That is heavenly union with the Lord Jesus. Anybody who is in that is in heaven. You have not to define and explain to such people what it means to be in the heavenlies in Christ. They know of what you are speaking. Spiritual geography is understood by those who walk up and down in Him and enjoy His fulness.
If you are not there, all that we can do is to be like the spies, and report upon it, and it is left with you to say whether you are going in or not. It is left to the crisis of faith or unbelief, just as it was of old. Do you believe that that is the Christ Whom God has presented as the Sphere of your life? If so, go up and possess; appropriate by faith the fulness that is in Christ for every need which arises, for every demand which confronts you... Let us face the whole issue in this definite way: Lord, it is clearly represented in the Word that You are the fulness of God for me! Here is a need, a spiritual need. In order that You should be glorified in me, I by faith take You to meet this need! That is very simple. That is almost the infant class of things, but it is a very effective way of proving the Lord. Do not sink back afterward and decline into discouragement and say, Nothing has happened! Stand your ground just as Israel had to stand their ground and prove thereby that the Lord had indeed given.
From: The Essential Newness of the New Creation - Chapter 4