We are told in the Bible that Jonah is ordered by God to go to Ninaveh... to deliver God's message of impending destruction... We're told that Jonah instead went elsewhere... in defiance of God.
Now... I ask you... what was Jonah's sin? Was it disobeying a command by God? Or was it the act of getting on the ship and leaving?
This may seem all a little pointless... so let me clear it up.
In another Biblical account... another man is commanded by God... and he also disobeys. In this case he is commanded to impregnate a woman. Instead he masterbates.
Was his sin masterbation? or was it disobeying God?
From that latter story the Catholics insanely extrapolate that all birtch control is sin.
Its amazing that they don't also find that travelling by ship is also a sin... since applying the same standard to each story requires it.
Catholic logic is often bizarre... but this is one of the most extreme cases. Its total lunacy.
The sin was not spilling his seed upon the dust. The sin was disobeying God. Just as Jonah's sin was not getting on a ship... but disobeying God's command.
So... Dear Catholic friend... before you preach about birth control to me... consider weather or not you've ever taken a cruise.