1 Tim 3:16 And without controversy great is the mystery of godliness: God was manifested in the flesh, Justified in the Spirit, Seen by angels, Preached among the Gentiles, Believed on in the world, Received up in glory.

Key Words 
 1) Without Controversy – Greek word is homologoumenōs meaning: Commonly agreed upon, Commonly confessed, No argument among us over this subject.
2)  Mystery – Greek word is mustérion meaning: Something hidden, Something not obvious, Something only known through revelation from God
3) Godliness – Greek word is eusébeia meaning: Someone’s inner response to the things of God which shows itself in godly piety or loving obedience to God. 
Thoughts

In this verse we are being exhorted towards the common understanding of the Christians of Paul’s day. To realize and appreciate the intense weight and large magnitude of the hidden plan of God that has been given to us by revelation from the Holy Spirit. We couldn’t have figured out this hidden plan for ourselves and it was completely unexpected. We couldn’t have dreamed up a better way than God’s sovereign plan to make us holy. Appreciating the enormity of what God has done for us will move us towards an inner response and change by the Holy Spirit. Gazing at God’s goodness in this plan will change our inner motivations into primarily being motivated out of love, awe, and thankfulness towards God. 
What is this plan? God came in the flesh. Jesus fully man and fully God, emptied Himself and became totally dependent on God. He did what we couldn’t do. He lived completely holy His entire life and did only what He saw His Father doing. He became our perfect sacrifice for our inability to be holy on our own, when He gave up His life and spilled His blood for us. Every radical claim Jesus made was proven correct by the Holy Spirit when the Holy Spirit raised Jesus from the dead. He ascended into heaven and sits at the right hand of God until the day when the time is ready and He makes His return. Because of Jesus’ once and for all sacrifice we can now hear Jesus’ good news and become sons and daughters of God. We get adopted into the family when we lay down our lives and trust completely in Jesus for salvation.