Listen my friend,
first of all he wasnt an active member at Kach at all, he was just a member for a short time.
Anyway, it doesnt really matter what he was and for how much time, the fact is that he supports territory exchanges with the arabs,
he wants us to gain control over the settlements in Judah and Shomron, but in exchange he will give the palestinians total control over temporarily-occupied-arabian-towns
and neighborhood.
This means that eastern Jerusalem which is occupied by arabs or Um Al Fahem will become Hamas's.
He will create a palestinian state in the very heart of israel.
Secondly, Liberman is very very Non-religous, therefore he will promote anti jewish laws, like allowing civil marriage, or selling non Kosher food at any place they desire.
Liberman is NOT good for the jews.