I would also state though that since God nethod of saving would be the same, do see many who have their misunderstanding on this topic still saved, but they really need to study the Bible and come to the correct understanding on what salvation really means form the perspective of the scriptures.
It isn't a matter of method
but rather of content
that is most important, although the method will be determined by the content (message). Once again... the gospel being preached and spoken in the overwhelming majority of churches today is ANOTHER GOSPEL; a lie which cannot and does not save anyone. The Spirit of God does NOT work through lies but only truth. It is the TRUTH that sets a sinner free, not the lies of the Evil One. IT is the TRUE GOSPEL which is the power of God unto salvation to everyone that believes. Believing in another gospel, or another Jesus or another Spirit, or anything other than the real gospel, the real Christ and the real Spirit produces only sure death... not life.
And think that the Lord Jesus meant that there were many who professed to being saved and serving Him, claimed to be Christians, but in the end, they were not ever really saved by Him!
Yes, in part that is true. The ones who address Christ as "Lord, lord..." show that they were part of the visible, earthly church and not pagans or heathens. They were teachers, pastors, evangelists, etc. and of course, regular members of churches. They were dedicated to the 'cause', read their Bibles, witnessed, were baptized, partook of the Lord's Table, and strived to live 'good lives'. Yet, Jesus' reply is most important to this MANY... not a few. Depart from me you workers of iniquity. The reason for their rejection wasn't because THEY didn't love Christ (profession), but it was because Jesus never KNEW them, for He knew them well enough to call them workers of iniquity. The word "knew" in this text means "love". So, what Jesus said was, "I never loved you, depart from me you workers of iniquity!"
Do you understand the solemnity of this text now? Does it shake you down to your very core? It isn't whether someone professes to love Jesus, to receive Him as Lord, or is baptized, goes to seminary and is ordained as a pastor, or lives an outwardly godly life, etc. What matters most of all is whether Jesus loves you and has paid the penalty for your sins and called you by His grace through the sovereign and secret regenerating work of the Holy Spirit, calling you inwardly by irresistible grace, granting you the desire and ability to repent of your sins through the profound guilt put upon your mind and heart and convincing you of your desperate need of Christ and His righteousness, etc. (Eph 1:4-13).