Paul tries to explain God the Father's great dispensation for mankind. The phrase, "blessed be" [Ephesians 1:3] is not a phrase that is used for human beings or anyone else. Put differently, only God is worthy of being blessed, because He has given His spiritual blessings to mankind through the redeeming work of Jesus Christ. 

Humans are selfish and self-centered. But God, gave up and sacrificed Himself for us and that is why we cannot help but give our thanks to Him and Jesus with our faith.

The "spiritual blessing in the heavenly places" is not a blessing that anybody can receive. God allows the sun to shine upon both the good and the wicked and He brings rain on both the believers and unbelievers, but such a blessing is not a "spiritual blessing in the heavenly places." The "spiritual blessing in the heavenly places" is a special blessing, a blessing that can be received and enjoyed only by those who have received the remission of their sins by believing in the Gospel while on this earth.

For believers, Jesus is the Beginning and the End, the Alpha and the Omega. Only those who believe in the Gospel , fulfilled by can receive all the spiritual blessing that belong to Heaven forever.