One other teaching often connected to the preaching of the Gospel is that of the Name of Jesus.
But when they believed Philip preaching good news concerning the Kingdom of God and the name of JesusChrist, they were baptized, both men and women. (Acts 8:12)
The apostle John tells us that our salvation lies in this Name:
but these are written, that you may believe that Jesus is the Christ, the Son of God, and that believing you may have life in his name. (John 20:31)
These things I have written to you who believe in the name of the Son of God, that you may know that you have eternal life, and that you may continue to believe in the name of the Son of God. (1 John 5:13)
Learning about and experiencing the Name of Jesus, God's Son and Christ, will bring us into greater union with Him and thereby, His Father and Spirit as well.