chrzecijaskiego
Chrzecijaskiego is not a standard entry in Polish dictionaries. It is typically understood as a nonstandard or misspelled form of chrześcijańskiego, the genitive singular of chrześcijański, the adjective meaning Christian. In standard Polish, the genitive form conveys possession or association and is used before masculine nouns, as in chrześcijańskiego kraju (of a Christian country).
The standard word chrześcijański derives from chrześcijaństwo (Christianity), itself from Latin Christianus and Greek Christianos. Polish
In typical Polish grammar, you would encounter chrześcijańskiego in phrases such as chrześcijańskiego dziedzictwa, chrześcijańskiego kraju,
If encountered as a surname, Polish -ski surnames decline similarly, so a hypothetical masculine form Chrzecijaski
See also: chrześcijański, chrześcijaństwo, listy polskich przymiotnikowych form, Polish spelling and grammar.