Three times in the New Testament God would speak.
The first time would be when Christ was baptized. The trinity was shown at this time after Christ was baptized. The Spirit of God would come down as a dove and lite upon Him. Then a voice from Heaven, God would speak. He would tell them that Jesus was His beloved son and with whom He was well pleased. No other way to be saved than through the name of Jesus Christ. What compels you to serve Christ?
When Jesus was walking along with the disciples He began to transfigure in front of them. This proved that He could have done this at any time instead of going to Calvary as He would do later. He didn’t have to go through the torments but chose to do so for the sake of our sins. God spoke to the disciples and told them that Jesus was His beloved Son which He was well pleased and He also told them to listen to Him. There is no other name but Jesus. All they wanted to do was to build a tabernacle in honor of Moses, Elias, and Jesus. There was no one to build for other than Jesus. There is none to be worshipped but Christ.
God spoke out loud to Jesus. He didn’t have to speak out aloud but He did in this instance. He told Jesus that He had glorified His name and He will glorify it again. How Jesus suffered and came sin for us glorified His father, God. Jesus Christ’s life was perfect and He glorified His God. Not only His life, but His death, and His resurrection. It was all about Jesus when He spoke.
When God speaks aloud, it’s terrifying. Of all of the times when God spoke it was terrifying to hear. All we would need to hear is spoken by Christ. The Spirit of God speaks directly to us. The gentle, kindness of His voice to our soul when He speaks. He does it in a way that’s not booming or thundering. The message should always be the same, through Jesus Christ and He alone is the way to salvation.