Those opposed to abortion have the opinions that 1. The human fetus is, from conception, a human being.
No, it's not. It is a cell that is developing towards being a human being. I personally believe that when it is capable of independent survival with ordinary care (i.e. given feeding but not specialist medical intervention) it is a full human being*. Many of the medical inteventions developed have led to the survival of early foeti, but often with costs in terms of subsequent impaired development. Remember that many societies have exposed neonates in "borderline" cases of doubtful survival ability. Consider that this may not be wicked evildoers abusing tiny children, but a sensible way of testing if an infant will be capable of a decent quality of life.
... a good definition of genuine pluralism -- an adult respect for the strong convictions of others.
Nobody has convictions much stronger than those who are prepared to kill themselves, and you, to get their point across. They may deserve respect, but only the outright foolish would tolerate them. Silence is not demanded of opponents, but to refrain from damaging physical action or coercion is.
*This has a corollary that people's right to medical or other care grows as they gain presence in the world. It makes sense to throw resources at an experienced adult that you wouldn't give to a new baby or a moribund person, and this is more or less what is done, when the playing field is level.