I was thinking (always dangerous with me).
The record for the most children in any family (in the UK) as far as I know is 18. This is held by a Free Presbyterian lady in Skye who married at 17 and who doesn’t believe in contraception OR NFP. She had her eldest child at 42 I think.
That means, in 25 years, she has had 18 children. In turn, that means that for 18x 9 months = 13yrs 6mths, she was not able to conceive. That means, in 11yrs 6mths she conceived 17 times. That means, of 136 potential conceptions, only 18 actual conceptions occurred.
Consequently, even the most fertile couple in the world have less than a 12% conception rate.
That means that the effectiveness of ‘do nothing’ as a form of birth control is around 90%.
Consider that most couples who are completely ‘open’ to children have only 5 or 6 in a marriage which may last for 20 fertile years, and the effectiveness may be as high as 96-97%
When people say that NFP has a 98% success rate, they are effectively saying that you are only around HALF as likely to conceive with NFP as you are if you just have sex whenever you like.
Even with condoms that are 99% effective, you are only ONE FIFTH less likely to conceive as you would be if you just did nothing.
Doesn’t this say something about the futility of trying to protect ourselves against God’s plan for us. Clearly I can see how planning a family can be useful, and particularly essential for those who risk complications in childbearing, but generally it seems that God has programmed most people to restrict their child-bearing abilities naturally (well, except a few oddly over-fertile ones, anyway).