Hebrews 6:4

[Dawid]

I don't understand the first word of this verse. Ele can be either "but" or "if" correct? If it's "but" what is he contrasting this to? There doesn't seem to be anything. But if it's an "if" then where is the "then"? Where there's an "if" there must be a "then."
Any help would be greatly appreciated.
Thanks.

Shalom,
Dawid