"I write so that you may know how you ought to conduct yourself in the house of God ... the mystery of godliness: God was manifested in the flesh ..." (1 Timothy 3:15-16).
We read, in 1 Timothy 3:16, of our deeply-held convictions concerning our Saviour, Jesus Christ: "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." Paul is not only speaking about beliefs that we hold with our minds - 'I believe this about Christ. I believe that about Him.' He's speaking about beliefs that change the way we live - "how you conduct yourselves in the house of God" (1 Timothy 3:15).
When Paul speaks about "the mystery of godliness", he's speaking about "God was manifested in the flesh". He's also speaking about "how we conduct ourselves in the house of God." This is the practical mystery - How can sinners live a godly life? This takes us beyond recalling the events of Christ's life. This takes us beyond, "I believe this about Him. I believe that about Him." This takes us on to Paul's teaching concerning the Holy Spirit: "your body is the temple of the Holy Spirit who is in you ... you were bought at a price; therefore glorify God in your body and in your spirit ... " (1 Corinthians 6:19-20).
When Paul writes to us about "how we conduct ourselves in the house of God", we may recall his description of our life (it's more than our body, it's our body and our spirit) as "the temple of the Holy Spirit." Paul is not only concerned about how we behave when we set foot in the house of God. He's concerned about our whole life. He's saying to us, "Walk in the Spirit, and you shall not fulfill the lust of the flesh" (Galatians 5:16).
What is the connection between "the mystery of godliness" - God was manifested in the flesh" - and "the mystery of godliness" - sinners saved by grace are led in the way of the Holy Spirit? - "You were bought at a price": If we really believe the things that happened to Christ and the reason that these things happened to Him ("for us and for our salvation"), how can we continue to live as if these things were not true?
How we conduct ourselves - in the house of God and in the whole of life: This is where the real strength of our faith will be seen. Strong faith expresses itself in godly living. A strong faith is always ready to ask the question, "How much is my life being changed by the Lord?"