NOTES for Eph 1:3-4
A very deep theology stands behind this blessing of the apostle Paul. The ‘adamic” fall of the human nature is not in a state to contain " all spiritual blessings " from God, but the Son of God, being incarnated, become the Son of Man, bears in Himself another "Christlike" human nature, sinless, and that’s why particularly in Christ God blesses eternal people ("in heavens") the blessing.
Before the creation of the world, God, having conceived man as a being possessing liberty, foresee in case of our fall Christ's salvific exploit, Who came in flesh so that connecting faith with Christ, we became partakers of His sinless nature and, thus, holy, pure and filled with love. So, God's choice turns out opened for us who believed in His coming, in His Birth, that we shall very soon be getting ready to celebrate; And the first of all the elected humanity becomes That, Who believed firstly, - Holy Virgin Theotokos.