Believest thou not that I am in the Father, and the Father in me? the words that I speak unto you I speak not of myself: but the Father that dwelleth in me, he doeth the works. Believe me that I am in the Father, and the Father in me: or else believe me for the very works’ sake.
The statements “I am in the Father” and “the Father in me” describes the closeness of the union between the Father and the Son. They are separate Persons, yet they are One as to attributes, character, and deity. This may be difficult to comprehend but whether we understand it or not, it doesn’t change the fact that it is true.