@Leadfoot,
Because the Holy Spirit explained it to me. With the verses. I ask a question and the Holy Spirit answers with verses. I asked Him about your question and this is what He said.
John 5:37-38
37 "And the Father Himself, who sent Me, has testified of Me. You have neither heard His voice at any time, nor seen His form.
38 "But you do not have His word abiding in you, because whom He sent, Him you do not believe.
(NKJ)
Heb 1:1-2
1 God, who at various times and in various ways spoke in time past to the fathers by the prophets,
2 has in these last days spoken to us by His Son, whom He has appointed heir of all things, through whom also He made the worlds;
(NKJ)
Now we as a people seen Jesus and heard Him speak. I hear the Holy Spirit speak to me every day.