I take into consideration what Paul wrote and how it coincides with ALL scriptura not just a single verse. And by the way I’m not saying anything, I’m simply relaying the message just like John relayed the message that Jesus gave to His 11 FAITHFUL APOSTLES in John 15. In John 15 Jesus told them to remain in Him, then He told them why they must remain in Him, then He explained the consequences of failing to remain in Him, then He explained the rewards IF they remain in Him. Now unless you believe that John 6:64 is incorrect then you would know that Jesus knew that every one of these men He is speaking to IS A TRUE BELIEVER and yet He still explains to them the necessity of remaining in Him. Anyone who does not remain in Him is cast away to wither and cast into the fire to be burned. So since we know they were undoubtedly true believers we know that even true believers can turn away from Christ which will result in loss of salvation. It doesn’t matter if they believed before or even if they still believe today, if they are not abiding in Christ they will burn in the lake of fire. So believing is not an automatic ticket into heaven. Abiding in Christ means that you are remaining in His teachings and His servant.
Do these people believe in Christ?
“"Not everyone who says to Me, 'Lord, Lord,' will enter the kingdom of heaven, but he who does the will of My Father who is in heaven will enter. Many will say to Me on that day, 'Lord, Lord, did we not prophesy in Your name, and in Your name cast out demons, and in Your name perform many miracles?' And then I will declare to them, 'I never knew you; DEPART FROM ME, YOU WHO PRACTICE LAWLESSNESS.'”
Matthew 7:21-23 NASB
Why were they rejected?
“"Therefore everyone who hears these words of Mine and acts on them, may be compared to a wise man who built his house on the rock. And the rain fell, and the floods came, and the winds blew and slammed against that house; and yet it did not fall, for it had been founded on the rock. Everyone who hears these words of Mine and does not act on them, will be like a foolish man who built his house on the sand. The rain fell, and the floods came, and the winds blew and slammed against that house; and it fell-and great was its fall."”
Matthew 7:24-27 NASB