For we are members of His body, of His flesh, and of His bones. – Ephesians 5:30

Mr. William Olney…very frequently spoke of our being one with Christ in “living, loving, lasting union”-three words which, in addition to being alliterative, are very comprehensive as to the nature of our union with Christ…It is a most wonderful union. The more you think of it, the more you will be astonished, and stand in sacred awe before such a marvel of grace. Well did Kent say-

“O sacred union, firm and strong,
How great the grace, how sweet the song,
That worms of earth should ever be
One with Incarnate Deity!”

This is a very cheering doctrine. He that understands it has an ocean of music in his soul. He that can really grasp and feed upon it will often sit in the heavenly places with his Lord and anticipate the day when he shall be with Him and shall be like Him. Even now, since we are one with Him, there is no distance between us, we are nearer to Him than anything else can ever be. The very idea of union makes us forget all distance: indeed, distance is altogether annihilated. Love joins us so closely with Christ, that He becomes more to us than our very selves; and though now we see Him not, yet believing, we rejoice with joy unspeakable and full of glory. ~ C.H. Spurgeon

https://www.blueletterbible.org/comm/spurgeon_charles/sermons/2244.cfm