Judisium
 

If a today,s old testament Jew sins, what must he do to get forgiven? Curious-One

Old Testament Jews? As opposed to what?

We are called, simply, Jews. Anything else is - other than recognizing which movement within Judaism we identify with - is both incorrect and offensive.

Jews do not call their scripture the Old Testament. We refer to Hebrew scripture as the Tanakh.

The short answer to your question though is repentence and the making of amends.

L'shalom,

Peter