Most Christian ethicists I know of, both Roman Catholic and Protestant, even while condemning both, do distinguish between the prevention of pregnancy (contraception) and the destruction of it, involving homicide, by abortion, IUD's or the pill. Killing a human of course is much more grave a sin than preventing a natural blessing...even if both involve sexual reproduction.
Many Christians, especially in evangelical Protestant circles (of which I am in...) oddly enough, have trouble distinguishing greater and lesser sins however.
All sin though involves lacking faith--and ultimately avoiding the blessings that come from walking by faith.
But to claim there is no scriptural basis for teaching that birth control is immoral is simply beyond credulity.
Christianity has always, unanimously declared that contraception is inherently wrong, based on the Onan incident and Natural Law.
Its only within the last 80 years, but primarily since 1960, that Protestantism has reinterpreted these issues to say that contraception is morally licit.
When Christian moral theology unanimously teaches that something is inherently evil, then certain subsets of Christianity only in the last several generations claim otherwise, that is by definition proof of apostasy in moral theology, one's personal interpretation of scripture notwithstanding.
If we disagree with the entire patrimony of Christianity on this issue, we cannot possibly be correct, and we must examine ourselves to find our error.