St Augustine did not consider all sex evil

Contrary to some Protestant claims, and the Pelagians of St Augustine's day, he did not view ALL sex as being sinful, rather he considered having sex outside of the purpose of procreation as sinful, but even then, if it were between a married couple it would be a venial sin (small sin that is not deadly). Here is what St Augustine says on this matter:

It is, however, one thing for married persons to have intercourse only for the wish to beget children, which is not sinful: it is another thing for them to desire carnal pleasure in cohabitation, but with the spouse only, which involves venial sin. For although propagation of offspring is not the motive of the intercourse, there is still no attempt to prevent such propagation, either by wrong desire or evil appliance.--St Augustine On Marriage and Concupiscence Book I Chapter

It should also be mentioned St Augustine refers several times to Marriage as being a sacrament (at least in some sense of the word) unlike the Protestants who deny it sacramental status in any sense.