Be careful with that statement.
If one believes in the Trinity and takes that saying literally, one has to believe that the Father keeps secrets from the Son and Holy Spirit which means that the Three Persons are not equal in majesty.
When Jesus says things like "only the Father knows", He's speaking from the man part of him, not Jesus as God, His choice not to know. The same when the two apostles asked to be seated on either side of Him in heaven, He told them that it wasn't His to give but the Father's, He was speaking as the man He was, not as God that He was.
He suffered and died as a man would suffer, not as God would, again, His choice.
Just my interpretation, yours most likely will vary and neither interpretation will affect your salvation or mine - still my "opinion".
My point was not about the trinity, but, the foolishness of man.