Jesus the Son is in God the Father and the Father is in the Son, so they are one. In mathematics, if A is in B and B in A, then it's a certainty that A and B are one. Union makes us one with God. When we surrender to God, we are in him; but how can God, so much greater than us, be in us? I am assured by the fact that Jesus gladly and willingly descended to earth to become one of us in order to save us. To be just like us, he asked John the Baptist to baptize him. He even washed the feet of his disciples to show his humility. In John 14, after promising that he would send the Holy Spirit to us, he said, "On that day you will realize that I am in my Father and you are in me and I in you." And that's how we become temples of the Holy Spirit. By instituting the Holy Eucharist, the Lord made it absolutely clear that he can dwell within us. So, believe, surrender, and receive the Eucharist, and we are one with God!