What is the number of spanish speakinh Christians in the world? (  in
terms of millions and per cent of world's  population. Use any def. of
Christian widely accepted by sociologist of religion and any
definition of Spanishing speaking widely used by scholars.

This is not intended as an authoritative answer, and is simply based
on my own knowledge and some fairly basic Googling. First, it isn't
clear whether you are referring to Christians who speak Spanish as
their first language, or wish to include those who speak Spanish as a
second language. However, according to this website -
http://www.nvtc.gov/lotw/months/january/Spanish.html - in 1999 there
were about 352 million first-language Spanish speakers, and about 417
million if Spanish as a second-language is included. Allowing for
about 1.5%p.a. increase in population, those figures have probably
increased to about 380 million and 450 million, respectively, today.

I would say that the vast majority of those people are nominally
Christian, but I doubt if anyone has any precise statistics,
especially for the figure including second-language Spanish-speakers.
The statistics for Christians in Spain and Mexico, which have the
largest populations of Spanish-speakers, indicate that  90% would be a
reasonable working assumption, which would bring the overall figures
down to about 340 and 400 million, respectively.

Since the total world population is at present about 6,500 million;
this would mean that Christians speaking Spanish as their native
language would be about 5% of the world population; and those speaking
Spanish as their native or second language would be 6%.

Spain had 104,170 'publishers', [Jehovah's Witnesses speaking to
people door to door]. This figure is taken from the 2005 world report
published by the ' Watchtower' society. It is taken that all speak
Spanish. This figure relates to Spain, and does not include Spanish
speaking congregations in other countries. Considering that Spain is a
major ' mainly Catholic' country, the figure is amazing when compared
to the Australian total of publishers at 61,444. A genuine number
could be calculated from visiting Catholic and Protestant websites,
and adding them to the above, very accurate, figures.