These are the lessons I learnt from the teaching of brother Eli which topic was: Proving God's Existence.
There was only one language spoken on earth because God spoke to Adam with only one language.
Genesis 11:1 And the whole earth was of one language, and of one speech.
The reason we know how to speak today is because God spoke to our Fathers in old time.
If God had not spoken to humanity, humanity would not have learnt God's language
Man was able to have understanding because God communicated with man. God taught man how to communicate by speaking to man
Adam the first man on earth learnt how to speak by hearing God speak. Adam learnt words because he heard it from God.
God transfered his wisdom, feelings and emotions to man through the old prophets.
Hebrew 1:1 God, who at sundry times and in divers manners spake in time past unto the fathers by the prophets,
Humans learnt how to speaking by hearing somebody speak. That person is God the father and that is very clear proof that God exists.
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From @tildy