The holy fathers of the Church say that we can have assurance of our salvation only by divine revelation from God. Otherwise, we cannot be the source of our assurance. Moreover, we cannot improperly interpret the Scriptures to give ourselves the impression that we are assured of our salvation. What I've seen many people do is say, "Look at this Scripture. It plainly says that you're saved!" No, brother, you're deceived. You interpret it very incorrectly. Who are you to pronounce a judgment on yourself or others? That is God's task, not yours. Otherwise, "hope that is seen is not hope" of salvation; such a faith is based on human rationalism, erroneous interpretation of the Scriptures, and self-assurance rather than God's assurance.
When over 2000 years of theologians say that there is no assurance of salvation apart from a personal divine revelation (not through the Scriptures), and when many say, "No one man can be right by himself on matters of dogma", then I must put my trust in the consensus of holy pious teachers of the faith, rather than renegades who were so puffed up in their minds that they created their own denominations.