CREATE TABLE table_45947 ("Ethnicity" TEXT, "Islam" TEXT, "Christianity" TEXT, "Judaism" TEXT, "Buddhism" TEXT, "Other" TEXT, "Atheism" TEXT)

What is the percentage of Judaism associated with Christianity at 2.51%?
SELECT "Judaism" FROM table_45947 WHERE "Christianity" = '2.51%'
SELECT "Judaism" FROM "table_45947" WHERE "Christianity" = '2.51%'