Note that Paul wasn't saying anyone believing that gospel would be accursed...only the one teaching it. So we need to be careful in how we treat those who are deceived by false doctrine. Jesus said to beware false prophets, false Christs...He said nothing bout such as being shut out of heaven as a result of being deceived. His judgements in this matter thank God, are more merciful than man's. Otherwise we would be having people left right and center claiming only their denomination...their view of scripture...their non Calvinist/proCalvinist/ to the excusion of all else....oh, sorry, we do have that already don't we. Having said that, there is surely a danger in being deceived. And we ought to at every opportunity to bring light and truth to others in the way...but be careful much on how we judge those who believe different to us...the heart itself is more deceitful than false doctrine...beware it isn't your own heart deceiving you.
There are Christians...genuine Christians, in every church...including LDS. Jesus does not accept us into HIs kingdom based on our proud boastful claims of knowing Him and having all our doctrinal ducks in a row (although truth matters) but rather on whether or not He knows us. His knowledge of us lies in our willingness to surrender to Him our minds, hearts, and soul...the whole being, to Him. Some in the more "out there" churches have done this, but God in His good time has not seen fit to bring them out yet; and that could be for any number of reasons. Light too much, too suddenly blinds...it does not reveal. So some seemingly languish in belief systems that others disapprove of...that however does not discount the possibility of those folk not living up to what light they have received.
My heart goes out to all Christians who having received light from God regarding their false beliefs, reject that light. And you will find them everywhere.
It is very misguided opinion you state & contrary to the Bible to tell people that they can be in a False cult that preaches a complete Corruption of Christianity that is at variance to JESUS teachings and tell them that they are Saved too. SDA is also a corruption of Christian teachings also, so it does not surprise that you are supporting Mormonism deception.
How about all the rest of the false spiritual paths that the Bible says don't lead to GOD, do you support them also telling people falsely that they can be saved and follow False ANY counterfeits to Christianity?
This is so much more then someone not having
all their theological & doctrinal beliefs correct like you dismissively stated.
Second Day Adventist--is False teaching also, that were received by Ellen White from deceiving spirits , how can anyone not realize this Fact if they are GOD fearing and submitted Christ Jesus follower? All through the Bible ,scriptures warn of False prophets ,False Teachers & wolves in sheep's clothing who attack from within the Church. Galatians 1:8 stated that Anyone who leads people astray with by preaching another Gospel then what Jesus & His Apostles taught is under a divine curse according to Apostle Paul's statements.
JESUS HIMSELF warned about being lead to destruction.
People who are members of a false cult & believe the tales of lying spirits can say that they "love" Jesus until the cows come home-but the proof as Jesus said is following His teachings not false teachings that have been added by lying spirits.
FYI, some occultists also believe that Jesus was a spiritual teacher and they "love" him but by applying the Bible scripture , it reveals that they do not know the real Jesus of Nazareth who died on the cross & rose from the dead, therefore, they are not Christians, even though they claim to love him, that is self-deception. John 10:27 Jesus said "my sheep know my voice & follow me". Matt 12:50 -Those who are His followers "do the will of His Father in heaven." Matt 12:50 is only found in the Bible scripture , not in following phony deceptive teachings of lying spirits.
The whole point of this demonic deception & the REASON Paul was so adamant & stern against it, is because FALSE teachings/ doctrines of demons whole purpose is to spiritually deceive people & to LEAD people away from God into Hell. It is what Satan has done since Eden.