Why the term "sponsor"?
Most of us probably first come across the word sponsor, when we do a sponsored walk or swim at school. In this sense, it tends to carry connotations of a financial supporter. In financial markets, a sponsor seems to mean a kind of referee who lends their reputation to some form of transaction. In sporting events, it is someone who supports financially in return for some kind of publicity. Amusingly if you translate sponsor into French and back again using Babelfish it gives sleeping partner (which at the very least is ambiguous in English). In other languages sponsors are referred to literal translations of godparents, aunts and uncles or supporters.
Our form of child sponsorship, which is directly linked to help for a child, is a bit different and we sometimes try to think of different expressions in English. Child Protectors sounds good but too much like the child protection agency, child guardians sounds too much like guardian angels, god parents sounds a little religious and although many of our supporters are Christian, many are not. So we stick to inviting people to sponsor a child and hope they will listen and find out a little more about what it involves.
Of course, not everyone has always thought that it is a good thing to sponsor a child. There was an article in 1982 by Peter Stalker in the New Internationalist objecting strongly to the concept as demeaning and derisory. As has been said elsewhere, differences between ways to sponsor a child mean that many of the objections are specific to a particular charity or practice. This means, of course, that a donor has a duty to find a responsible charity, sensitive to the child's best interests (as per the UN convention of the rights of a child: the child's best interest must be a central consideration). But then the donor also needs to pay attention to plenty of other aspects of a charity's work (e.g. fundraising costs) so there is no safe and easy way to help.
1911 definition of Sponsor
After writing the above I found this definition of a sponsor in the 1911 Encyclopedia Britannica:
SPONSOR (from Lat. spondere, to promise), one who stands surety for another, especially in the rite of Christian baptism, a godfather or godmother. The practice originated not in infant baptism, but in the custom of requiring an adult pagan who offered himself for the rite to be accompanied by a Christian known to the bishop, who could vouch for the applicant and undertake his supervision, thus fulfilling the function performed in the Eleusinian mysteries by the mystagogus. The Greek word for the person undertaking this function is hvito~os, to which the Latin susceptor is equivalent. The word sponsor in this ecclesiastical sense occurs for the first time, but incidentally only, and as if it were already long familiar, in Tertullian's treatise De baptismo (ch. 18), where, arguing that in certain circumstances baptism may conveniently bepostponed, especially in the case of little children, he asks, For why is it necessary that the sponsors likewise should be thrust into danger, who both themselves by reason of mortality may fail to fulfil their promises, and may also be disappointed by the development of an evil disposition ?
The sponsors here alluded to may have been in many cases the actual parents, and even in the 5th century it was not felt to be inappropriate that they should be so; Augustine, indeed, in one passage appears to speak of it as a matter of course that parents should bring their children and answer for them tanquam fidejussores (Epist. . . . ad Bonif. 98), and the oldest Egyptian ritual bears similar testimony. Elsewhere Augustine contemplates the bringing of the children of slaves by their masters, and of course orphans and foundlings were brought by other benevolent persons. The comparatively early appearance, however, of such names as corn patrcs, commatres, pro patres, proinaires, patrifli, rnatrinae, is of itself sufficient evidence, not only that the sponsorial relationship had come to be regarded as a very close one, but also that it was not usually assumed by the natural parents. How very close it was held to be is shown by the Justinian prohibition of marriage between godparents and godchildren. On the other hand, the anciently allowable practice of parents becoming sponsors for their own children, though gradually becoming obsolete, seems to have lingered until the 9th century, when it was at last formally prohibited by the council of Mainz (813). For a long time there was no fixed rule as to the necessary or allowable number of sponsors and sometimes the number actually assumed was large. By the council of Trent, however, it was decided that one only, or at most two, these not being of the same sex, should be permitted. The rubric of the Church of England according to which there shall be for every male child to be baptized two godfathers and one godmother, and for every female one godfather and two godmothers, is not older than 1661; the sponsors are charged with the duty of instructing the child, and in due time presenting it for confirmation, and in the Catechism the child is taught to say that he received his name from his godfathers and godmothers. At the Reformation the Lutheran churches retained godfathers and godmothers, but the Reformed churches reverted to what they believed to be the more primitive rule, that in ordinary circumstances this function should be undertaken by a child's proper parent. Most churches demand of sponsors that they be in full communion. In the Roman Catholic Church, priests, monks and nuns are disqualified from being sponsors, either because it might involve their entanglement in worldly affairs, or more probably because every relationship of fatherhood or motherhood is felt to be in their case inappropriate. The spiritual relationship established between the sponsor and the baptized, and the sponsors and the parents of the baptized, constitutes an impediment to marriage