Re: Is it wrong for Christians to practice Jewish traditions?
It is somewhat "fashionable" these days for Christians to explore the Jewish roots of Christianity (which is unobjectionable) and to indiscriminately take on Jewish practices and observances (which can be objectionable). Unfortunately, most Christians do not know Judaism well enough to understand that it can be highly offensive to Jews for Christians to treat Jewish traditions and observances as though they were toys to be picked up, tried out, and discarded at whim by non-Jews.
There are some Jewish practices that should never be "co-opted" by non-Jews. For example, Christians who are not of a Jewish background should never presume to wear a tallit (prayer shawl) or tefillin (phylacteries). Such an action would be gravely offensive to Jews, who believe that the tallit and tefillin should only be worn by a fellow Jew. (Christians of a Jewish background may retain their traditional observances under certain circumstances, but should be sensitive to the feelings of Jewish family and friends who might be upset to see such observances performed by someone they no longer consider to have a right to perform them.) As to other practices and observances, I can only recommend that Christians be very sure of what they are doing before presuming to, for example, hold a seder, wear a yarmulke, light a menorah, etc.
Taking on Jewish practices and observances of any kind is a very serious matter and not to be done merely because doing so seems "cool" or a "good idea." If in doubt, don't. It is far better to stick to one's own traditions than to risk hurting and upsetting other people by indiscriminately co-opting theirs.