It's true that the Catechism "attempts" to harmonize these incompatible positions, but it cannot be done. The teaching of the Catholic faith is that which has been believed and taught "always and everywhere" by all the faithful of all time, not by one small group of Catholics for one short period of time. What has been always taught and believed by all Catholics is that you must enter the Catholic Church in order to be saved.
Is this an ex cathedra position or is the attempt to harmonize the "incompatible" doctrines? I seek to know, not argue.