"ce en quoi" (eg : "ce en quoi nous croyons" ), "ce pour quoi" (eg : "ce pour quoi nous luttons" ), "ce vers quoi" (eg : ce vers quoi nous tendons" ), "ce par quoi ( eg : "ce par quoi nous vivons" ), all these are correct and usual in French, if it is what you were in doubt about
Thank you so much for kind explanation. (Sorry, I thought that you had forgotten to delete a word or two). May I ask you if the following is also correct: "Lutter pour c'en quoi on croit peut durer longtemps." "Se battre pour ses convictions peut prendre du temps."
Thank you so much in advance for your time and efford! ;-)
"c'en quoi" is not correct, while "ce en quoi" is correct. ("ce" and "en" don't sound the same, and "c'en quoi" would be ressembling "sans quoi" too much, which has a different meaning)
"Se battre pour ses convictions peut prendre du temps" is perfect!