I enumerated the elements that point to the former Catholic being badly informed: the ideas that the Church does not teach or know the scripture, that the sacraments are rituals, that obedience to rules saves, that personal relationship with Jesus cannot exist in a liturgical hierarchical church -- all come from ignorance of Catholicism.
Do these differences "mean little to God"? The scripture tells us that they are of great concern to God: St. Paul was furious that there were divisions in Corinth; Christ prayed fervently that we be one as His Father and He are one. Surely we can cooperate, for example, in pro-life politics, and very much in Protestantism remains Catholic and is therefore authentic Christianity, even though it is rarely acknowledged. However, the religious belief dictates culture and culture drives politics; it is hard for me to observe the centrifugal trajectory of Protestant Christianity in the past few centuries and not to expect even weaker bonds between us in the future.
The division Paul spoke of was not about things like what title to call Mary by. The divisions Paul spoke against was that who to follow. Some were saying Paul, others were saying Appolo, others were saying Christ. That is what Paul was upset by. People are saved by belief in Christ Jesus, not by any church or its numerous doctrines.