Three 16 Apr 2019
In the bible it says that the testimony of one is not valid. There are at least two witnesses needed to have a valid testimony.
Now a singular God being greater than the universe can not easily give testimony about himself. He did send his Son Jesus to give testimony. The Son is one with the Father. Sending his Son was not enough. He also did send his Spirit. So both the Son and the Holy Spirit, give here on earth testimony about God the Creator. They all three agree.
Three little men
Easy to say
Yes, that is true. I am not able to convince you about the existence of God. But God has send two trustworthy witnesses. You can invite both Jesus and the Holy Spirit to give testimony.
To simplify it even:
You must believe in Jesus and be baptized. Then He promises to give you the Holy Spirit. There is still faith required.
God did send his Holy Spirit.