What you need to know and understand before preaching and teaching the Gospel?

Chapter one
You must know who God has revealed the gospel to

In the book of the old testament, the gospel was revealed to the prophets of old
RF: 1 Peter 1:10-12
(NIV) Romans 16:25-26, Acts 3:19-26

In the book of the new testament, Christ Jesus revealed the gospel to His twelve apostles
RF: Matthew 16:13-20, Luke 24:25-27 & 44-46, Ephesians 3:3-5

Christ Jesus also revealed the gospel to Saul, who was known as Paul
RF: Galatians 1:6-24 (see vs.12, 16), Ephesians 3:1-5

Christ Jesus has also revealed the gospel to Godwin Ovie Godwin the Apostle of the Gospel

Understand the terms used for the gospel revealed
“.... according to my gospel, and the preaching of Jesus Christ, according to the revelation of the mystery, which was kept secret since the world began, But now is made manifest and by the scriptures....” Romans 16:25-26
“.... the gospel which was preached of me is not after man. For I neither received it of man, neither was I taught it, but by the revelation of Jesus Christ....” Galatians 1:11-12
“.... how that by revelation he (i.e. Christ Jesus) made known unto me the mystery; (as I wrote afore in few words, whereby, when ye read, ye may understand my knowledge in the mystery of Christ) which in other ages was not made known unto the sons of men, as it is now revealed unto his holy apostles and prophets by the Spirit....” Ephesians 3:1-5
“.... to make known the mystery of the gospel....” Ephesians 6:18-20
“.... the word of the LORD is with him”. This word is mostly common among Israel and the prophets. The word of the Lord is the gospel 2 Kings 3:11-12, 1 Samuel 3:1, 21, Jeremiah 1:4-11, 1 Peter 1:25