Apostle John taught that Mary is in heaven, with a crown, and fighting for the Church (Rev. 12). However, we don't' know the entirety of what the Apostles taught from scripture alone; this is why an authentic Christian should learn from what the Holy Catholic and Apostolic Church teaches through the entirety of time and not merely the written record of the canonical scripture.
if anyone taught a different gospel than they did we were to consider them accursed.
The teachings of Protestant charlatans from Luther on are indeed accursed. That is because unlike the Holy Church they contradicted the Gospels when they invented a "church" without priests and sacraments, and taught the counter-scriptural theories of Sola Scriptura and Sola Fide.
Please show where John "taught" that the sign in heave was Mary. I know that is what your Church teaches but I don't recall ever seeing that John taught that.
>>The teachings of Protestant charlatans from Luther on are indeed accursed.<<
Ok, so you think the "Protestant charlatans" as you call them are accursed. Since I'm don't align with Protestants and agree that many of them are also teaching "another gospel" that's not the subject we are talking about. We are talking about ANYONE who teaches "another gospel". Paul said "But even if we or an angel from heaven should preach a gospel other than the one we preached to you, let them be under God's curse!" Now, if you choose to defend the Catholic Church I'm asking you to show where the apostles taught the assumption of Mary.