Let me break down for you how this can be done:
Encourage free thought policy.
Make sure you do not have active buildings that encourage unity.
Wait for a faction that has the ethics you desire to pop up.
OPTIONAL - Check them out in the faction's screen, to see what you can do to increase their attraction to your population and overall happiness.
Select Manage the faction, and select Embrace faction.
Seriously, you chose Fanatic Militarist for the combat bonus, Spiritualist for the governing ethics attraction bonus (and perhaps psionics), and Imperial rule under the assumption that it gave you carte blanche in what you can do. You complain about power gaming, but judging by your picks that is EXACTLY what you where doing.
Ethics and government are RELATED in this instance. The ETHICS represent how your GOVERNMENT behave, just as your CIVICS does. In this case, it is the guiding framework of how your emperor decrees, and the history they uphold while they are on the throne. Your empire places martial prowess above all others, with being spiritualism the second most important thing in people's lives and history. If you want to change the cultural basis of your empire to embrace exclusivity as one if its priorities, then you have to evolve it to that place.
I think the confusion here is that you feel you are roleplaying the emperor. You are not. You are roleplaying the EMPIRE as a whole. The emperor is just an aspect of that empire.
Encourage free thought policy.
Make sure you do not have active buildings that encourage unity.
Wait for a faction that has the ethics you desire to pop up.
OPTIONAL - Check them out in the faction's screen, to see what you can do to increase their attraction to your population and overall happiness.
Select Manage the faction, and select Embrace faction.
Seriously, you chose Fanatic Militarist for the combat bonus, Spiritualist for the governing ethics attraction bonus (and perhaps psionics), and Imperial rule under the assumption that it gave you carte blanche in what you can do. You complain about power gaming, but judging by your picks that is EXACTLY what you where doing.
Ethics and government are RELATED in this instance. The ETHICS represent how your GOVERNMENT behave, just as your CIVICS does. In this case, it is the guiding framework of how your emperor decrees, and the history they uphold while they are on the throne. Your empire places martial prowess above all others, with being spiritualism the second most important thing in people's lives and history. If you want to change the cultural basis of your empire to embrace exclusivity as one if its priorities, then you have to evolve it to that place.
I think the confusion here is that you feel you are roleplaying the emperor. You are not. You are roleplaying the EMPIRE as a whole. The emperor is just an aspect of that empire.