Education means having a basic knowledge of all subjects. But a person cannot get that knowledge if he/she cannot read or write. So a person cannot become educated without being literate. But if you are literate you wont face much problem in attaining education at an point of your life. All you need is just a book to get get education. It means that if you are literate you have the potential to become educated and hence it is the same as being educated.
Claiming that education is not possible without literacy does not make being literate the same as being educated.
The definition of literacy is being able to read and write. So one can argue that being literate means that you are educated in reading and writing.
However being educated usually refers to more than knowing how to read and write. One can use literacy to be further educated in other things, but literacy is neither equal to education, nor does one need to be literate to be educated in something.
Literacy is defined as the ability to read and write but the meaning of literacy is much beyond that. Literacy means the ability to convey message and understand a message. And if you're saying that literacy is not required to be educated then why we waste 2 to 3 years of our life for learning alphabets, words and there pronounciation. Why don't we start learning maths or history.
And as you're saying that literacy is education of reading and writing, you are yourself proving that literacy is education. This point is contradicting your argument.