Question: "What is the mystery of God referred to in the Bible?"
Answer: The Bible tells us that the mystery of God is Jesus Christ: “My purpose is that they may be encouraged in heart and united in love, so that they may have the full riches of complete understanding, in order that they may know the mystery of God, namely, Christ, in whom are hidden all the treasures of wisdom and knowledge” (Colossians 2:2–3).
A “mystery” in the New Testament is something that had at one time been hidden but is now revealed to God’s people. Jesus spoke of “the mystery of the kingdom of God” (Mark 4:11, NAS) that He was at that point revealing to His disciples. The apostle Paul used the word mystery 21 times in his Epistles. In each case, the “mystery” involved a wonderful declaration of spiritual truth, revealed by God through divine inspiration. A mystery is that “which was not made known to people in other generations as it has now been revealed by the Spirit to God’s holy apostles and prophets” (Ephesians 3:5).
The mystery of God’s will is that “which he purposed in Christ, to be put into effect when the times reach their fulfillment—to bring unity to all things in heaven and on earth under Christ” (Ephesians 1:9–10; cf. 1 Corinthians 2:7; Revelation 10:7). The mystery of God is the consummation of God’s plan in bringing His kingdom in Christ to fulfillment. The kingdom had long been prophesied, but the how and the when and the by whom was not clear until the time of Christ. It is in Christ that God has been manifested to all of mankind. As Jesus said, “Anyone who has seen me has seen the Father” (John 14:9).
Paul said that he had been commissioned to preach “the word of God in its fullness—the mystery that has been kept hidden for ages and generations, but is now disclosed to the Lord’s people” (Colossians 1:25–26). That is, it is through the apostles that we have been given the capstone of Scripture; their writings, all of which point to Christ—represent the final disclosure of God’s Word to mankind.
There is no understanding of God apart from a personal relationship with His Son (Matthew 12:50; John14:23; 2 John 1:6). Christ is the “mystery” revealed to those who believe—as is the mystery of “Christ in you, the hope of glory” (Colossians 1:27). The key to having the “full riches of complete understanding” (Colossians 2:2) is to be born again by the power of the Holy Spirit. “The Spirit searches all things, even the deep things of God” (1 Corinthians 2:10).
Paul tells us that, “beyond all question, the mystery from which true godliness springs is great.” Then he records what may be an early hymn of the church: “He [Jesus] appeared in a body, was vindicated by the Spirit, was seen by angels, was preached among the nations, was believed on in the world, was taken up in glory” (1 Timothy 3:16). In that short paragraph, the Bible reveals the heart of the gospel, the mystery of “true godliness.” The secret of being godly was hidden but is now revealed. It is to those who believe in Christ that the mystery is made known (1 Corinthians 2:7–14; Colossians 1:27). We come to learn that we of our own volition cannot please God; we must depend on Christ (2 Corinthians 3:5). As a man, Jesus lived a perfect life (2 Corinthians 5:21; Hebrews 4:15; Hebrews 7:21), and so He is a perfect example of how to live. As God, Jesus gives us the power to do what is right. It is possible to live a godly life—through the power of Christ (Philippians 4:13).
God has revealed His complete Word to His saints (Colossians 1:26) who have “heard and learned” the gospel (John 6:45; cf. Romans 10:17 and John 3:16–18), and it is they alone who fathom “the glorious riches of this mystery” (Colossians 1:27). In its fullest sense, the “mystery of God” is God’s plan of salvation through Jesus. We would never have been able to comprehend the way to eternal life without the coming of Jesus, His death and resurrection.