The first thing to take into account is your target market. Do you expect that the kids will be able to sell to their classmates at school, or to their friends outside of school? If so, you'll want to choose a fundraiser that appeals to kids, like chocolate. If you think that most of the fundraising will be done out in the community, then you may want to look at some fundraising ideas that appeal to a broader age range.
Catalog fundraisers can be great for this, as can magazines. Secondly, when fundraising for Christian schools you want to take into account how large your group is, and what you estimate your overall selling power to be. The kids may be enthusiastic, but many of them will also have no experience with fundraising, and will need help from parents.
Even some of the parents may not have had much fundraising experience before. If you have a small or inexperienced fundraising team, Christian school fundraising can be more of a challenge, but it can be just as rewarding as for large groups.
You just want to look at appropriate fundraising ideas, like scratch cards or pizza cards, that will keep costs low and profit high. Thirdly, you need to think about how much money you need, and how that affects your choices. Lollipop fundraisers are great but if you need to make a lot of money, it would take you forever.
Choose instead a Christian school fundraiser that is high on profits and brings in a decent amount with each sale.