Magic Man
Reaper of Conversation
There is no getting to the premise through logic. A premise is a statement preceding a conclusion. A premise alone is neither logical or illogical. It is a component of an argument. An argument is what constitutes the domain of logic. You have confused a part for the whole.
To charge a premise i.e. 'a person walking on water is illogical' is a non sequitur. One can challenge the truth value of the statement, but that is distinct from logic proper. As previously explained: logic is formal. The content is irrelevant to the force of logic. The second example's form is:
A is B
B is C
Therefore, A is C.
One's discomfort with A, B or C does not speak to the validity and thereby the logic of the argument. The content of an argument can be filled with any number of premises or truth claims, religious or no.
A claim can be logical or illogical. You make a claim in a context. Jesus walked on water. That claim is in the context of the physical world we all know and experience, where a person walking on water is illogical. It's not just an argument that can be illogical, a statement can be too. Although, if you want to look at it another way, you could say that the argument that leads you to that premise is illogical, which then means the premise is illogical.
"1.according to or agreeing with the principles of logic: a logical inference." This is the definition of "logical" from Dictionary.com.
Using this definition, "Jesus walking on water" is not a logical inference from our experiences in our daily life. Therefore it is an illogical premise.