making known to us the mystery of his will, according to his purpose, which he set forth in Christ (ESV)
There are so many in this life that think that God is a great mystery. In fact, many view God as existing, but unknowable. He is just too mysterious and above them that they fail to reach out and have a relationship with him. I believe that many of those very people who claim that God is such a mystery want to keep him that way. They have no actual intentions of solving the mystery of God.
The late Christian singer, Keith Green, said:
"You're so proud of saying you're a seeker
But why are you searching in the dark
You won't find a thing
Until you soften your heart"
To those who want to claim to be seeking out the mysteries of God, without sincerely seeking him, I have news for you. You are missing out on the greatest revealed mystery of all time! One of the things that amazes me about God is that he goes out of his way to reveal himself! Hear the psalmist's words:
 The heavens declare the glory of God, and the sky above proclaims his handiwork.  Day to day pours out speech, and night to night reveals knowledge. (ESV)
In fact, God has made himself so clear through the revelation of his Creation that men are without excuse who would keep God a mystery:
 For what can be known about God is plain to them, because God has shown it to them.  For his invisible attributes, namely, his eternal power and divine nature, have been clearly perceived, ever since the creation of the world, in the things that have been made. So they are without excuse. (ESV)
The mystery has been revealed. Paul tells us in verse 9 of Ephesians 1 that God is "making known to us the mystery of his will, according to his purpose, which he set forth in Christ." Throughout history God has revealed himself in many ways. Creation. Prophetic words. Miracles. But all of this wonderful revelation culminates in Jesus Christ. The mystery of God's will is set forth in Christ.
Do you catch the beautiful significance? God does not just give us hints, shadows, and shades of truth that keep us guessing. He has given us his perfect son, Jesus Christ.
Mystery solved. God has revealed himself fully in Jesus Christ. You can know Jesus! Are you a seeker? Search is over. Ask Jesus to forgive your sins. Receive him as your Savior. Believe that he is God's son. I close with the beautiful words of the Apostle John:
 He came to his own, and his own people did not receive him.  But to all who did receive him, who believed in his name, he gave the right to become children of God,  who were born, not of blood nor of the will of the flesh nor of the will of man, but of God. (ESV)