Q: If you aren't Jewish, why do you do Jewish things?
A: Many of the things G-d commanded in Scripture were explicitly given to Israel (i.e. the Jews) but were intended for all peoples who call upon His Name. (See Numbers 15:16, Acts 26:23).
Followers of the Messiah Yeshua do these things in imitation of Him and in obedience to Him in order to honor and obey Him out of love (John 14:15).