You may or may not be a very religious person. Regardless, there’s a good chance that you don’t want your marriage/family to be based on atheism. Atheism may be an issue if you choose a wife from Russia or China (these countries have religion, but atheism is more prominent). You also may not be comfortable marrying a Buddhist—a likely issue if you marry a woman from some parts of Asia (China, Thailand, etc).
Most Filipinas are from a Roman Catholic background. Religious devotion varies, but Filipinas in general have some sense of devotion to God and the church. They tend to be open to other forms of Christianity (Protestant, etc) as evidenced by the success of other denominations in the Philippines.
In summary, Filipinas have a Christian/Catholic worldview, which may not be the case for women from other countries. This is another factor which makes Filipinas more compatible with Westerners.