The Gospel of Thomas is a New Testament-era apocryphon discovered in 1945 in Egypt. It contains passages that are similar to 'look within' to find 'Buddha nature' or 'universal Brahma'. The quotes below show the similarity:
These are the secret sayings that the living Jesus spoke and Didymos Judas Thomas
recorded.
1. And he said, "Whoever discovers the interpretation of these sayings will not
taste death."

3. Jesus said, "If your leaders say to you, 'Look, the (Father's) kingdom is in
the sky,' then the birds of the sky will precede you. If they say to you, 'It is in the
sea,' then the fish will precede you. Rather, the (Father's) kingdom is within you and it
is outside you.

When you know yourselves, then you will be known, and you will understand that you are
children of the living Father. But if you do not know yourselves, then you live in
poverty, and you are the poverty."

17. Jesus said, "I will give you what no eye has seen, what no ear has heard, what
no hand has touched, what has not arisen in the human heart."

24. His disciples said, "Show us the place where you are, for we must seek
it."

He said to them, "Anyone here with two ears had better listen! There is light
within a person of light, and it shines on the whole world. If it does not shine, it is
dark."

26. Jesus said, "You see the sliver in your friend's eye, but you don't see the
timber in your own eye. When you take the timber out of your own eye, then you will see
well enough to remove the sliver from your friend's eye."

69. Jesus said, "Congratulations to those who have been persecuted in their
hearts: they are the ones who have truly come to know the Father.

Congratulations to those who go hungry, so the stomach of the one in want may be
filled."

70. Jesus said, "If you bring forth what is within you, what you have will save
you. If you do not have that within you, what you do not have within you [will] kill
you."

77. Jesus said, "I am the light that is over all things. I am all: from me all
came forth, and to me all returned.

Split a piece of wood; I am there.

Lift up the stone, and you will find me there."

The mystic tradition of Christianity have similar expressions before the Gospel of Thomas is rediscovered. Does it mean 'all religions are the same?' Only if red and green are the same color.