See who is the doubter, who is the thinker. It is the ego. Hold it; the other thoughts will die away - the ego will be left pure. See the source from where the ego arises and abide in it. That is pure consciousness.
Ramana MaharshiDoes one require proof of one's own being? Only remain aware of yourself and all else will be known.
Ramana MaharshiNobody doubts that he exists, though he may doubt the existence of God. If he finds out the truth about himself and discovers his own source, this is all that is required.
Ramana Maharshi