Just remember to save your game (when you are at the pub for the second time -before walk down to tunnel- ) ,because you need to load your saved game for getting other achievements ; Meshugga, Mensch, Shmulky, Shonda for the Goyim, Ubermensch.
And be careful, when you open Steam Overlay (Shift+Tab), dialogues could be buggy. That's why we removed black cencor bar; already Overlay is bugging, with spoiler bar you can't read clearly.

You need to choose "rabbinical response" in every single dialogue, but when you talk with Mrs. Lauder don't choose "Rabbinical response", just talk with other two options. If you do that correctly, you will get this achievement as soon as possible when you go out to balcony with Zelig.

Story related, you cannot miss it.

Combine your two notes; Joe DeMarco and JDM.

Don't use a "rabbinical response" on Mrs. Lauder ever.

Just talk to her with other two responses.

Question Amos Zelig about his involvement with Ethan Goldberg and Jack Lauder's deaths.
I think you cannot miss this.

Kill Joe Demarco
Important:
When you visited the pub second time, Joe Demarco says "follow me'' and then save your game. You can load your saved game for getting other achievements. For killing him, choose "Don't show mercy" option.

Spare Joe Demarco
When you visited the pub second time, Joe Demarco says "follow me'' and then save your game. For sparing him, choose "Show mercy" option.

Kill Joe Demarco and Spare Amos Zelig.
Just choose "Don't show mercy" to Joe and after a fight with Zelig, choose option as "Knock him out".

Spare Joe Demarco and Amos Zelig.
Choose "Show mercy" to Joe and after a fight with Zelig, choose option as “Knock him out”.

Kill Amos Zelig.

Choose “Throw him over” option.

Don't get hit during the fights with Joe Demarco and Amos Zelig.

Well, here are the dialogues for having no damage from Demarco and Zelig ;
(please don't copy paste, i played this scene more than 5 times for getting true dialogue!)

Joe Demarco ;

-Rabbinical response.
-Do you really think you'll get away with this?
-How does a twelve year old commit murder ? ?
-Do you do everything people ask you to ??
-What happened to you ? Why you so angry?
-Why are you being so defensive ?
-Are you hiding from something ?
-Are you hiding behind that knife ?
-Care to prove it ?

Amos Zelig ;

-Who do you think I am ?
-You call yourself a Jew ?
-How can you face God knowing what you have done?
*throw punch*
-Are there others like you ?
*throw punch*
-Is this how rabbi acts?
*throw punch*
-How can you live like with yourself?
-You really think God will understand your action ?
*throw punch*
-Are you happy with this life, Zelig?
-Do you think a rabbi should act this way ?
*throw punch*
-I ask again : How can you live with yourself ?
*throw punch*

And done.