Father David C. Trosch #fundie trosch.org
Natural sexual activity are those acts between an adult male (preferably 25 years of age or older with reasonable financial stability and maturity) and a female who has reached an age of sufficient maturity to responsibly bear children as God wills (husband and his wife).
Procreation may not by intent be excluded whether by natural means or artificial means. Scriptural limits are set upon the days of a woman's cycle when sexual intercourse is permissible. Probable fertility occurs at the beginning of the permissible duration for moral intercourse as shown in the story of Bathsheba's pregnancy.
All focused ejaculations of a human male must be deposited within the vagina of a mature human female. The activity may not have been intentionally rendered infertile either by the male or the female. A woman may only receive sperm from a human male in the approved natural manner. All other two party (human or lower animal) sexual activity wherein one or both participants are human is condemned as unnatural. All sexual activity between near relatives or where one is a minor is condemned even if otherwise considered as natural.