God.
1. The Scriptures. The miracles that Jesus performed fulfilled all that was written of the Messiah by the prophets (Isaiah 61:1-2, Luke 4:16-20).
2. The miracles themselves proves Jesus was the Anointed One of God (John 3:2).
You men of Israel, hear these words; Jesus of Nazareth, a man approved of God among you by miracles and wonders and signs, which God did by him in the middle of you, as you yourselves also know: Acts 2:22
3. The prophecy spoken by Christ concerning the destruction of the Temple was fulfilled.
Jesus left the temple and was walking away when his disciples came up to him to call his attention to its buildings. “Do you see all these things?” he asked. “Truly I tell you, not one stone here will be left on another; every one will be thrown down.” Matthew 24:1-2
Anyway, since you are unable to prove that the miracle at Fatima is from God, why should I believe in it? Didn't the LORD say we should ALWAYS test the spirits to see if they are from Him (1 John 4:1, 2 Peter 2:1, Matthew 7:15)?
PS. I was not asking for scientific proof. All I want is Scripture backing that the so-called miracles experienced by those 3 little children was from God.