This phenomena is obvious in singapore and I see the following
reasons, but only for the chinese community.
1)Christians here are mostly english speaking. Generally the
english speaking families here are in the high or middle income
group. Civil servants (esp. the senior ones, since colonial time),
and all professionals speak english. That is why christianity is
regarded as western religion, angmoh ga.
2) on the other hand, chinese speaking only or those who quit
schools before 0 level and turn to speaking dialects and english
chinese form the majority of the population, in the middle or lower
income group or the grass root level. Most of the 1 million
buddhists, 200,000 taoists are among them and the others simply
practise chinese traditional rituals. There are not many christian
churches that cater to this group of ppl.
3) There are some very rich chinese speaking only singaporean,
mostly in their own business but they are usually very strong
buddhists or simply cannot accept christianity which to them is
western culture and influence.
4) Christianity holds very strong position against gambling and
unhealthy lifestyle, whereas followers of other religions believe
that it is the good deeds they do that count. IMHO, those who
gamble will never be rich.
Christians are still the minority among singaporen. Many churches
are sending missionaries to thailand, india and other distant
places, but how many churches, especially the english speaking
ones, conduct ministry to reach the poor, chinese speaking
populations in singapore?? well, these ppl usually have very strong
traditional religious background and are difficult ppl, plus home
ministry is definitely less noble sounding than overseas mission,
leave it to the chinese churches, i suppose. 
