True believers, as Scriptures state, are saved eternally. Period. They cannot “lose” what they did not “earn”. Scripture is very clear about God’s election being unconditional and irrevocable. Apostasy = those who “tasted” but were not saved (see Judas Iscariot for a prime example: sent out by Christ with the others, ate with them, witnessed the working of the Holy Spirit, knew Christ intimately, but was not saved). Once saved, NO ONE snatches them from the Father’s hand (John 10:28-29). Here are many more to that effect: https://www.openbible.info/topics/eternal_salvation
The word apostasy means to move away from one’s place or standing. Therefore one who was “never really saved” is one who’s place or standing has never changed. Therefore an apostate is one whose standing has changed from being saved to being lost. An apostate, one who has fallen does not refer to someone who has “never been saved”.
Judas was one who was in a saved standing (Matthew 10) but fell by transgression. Again, the word ‘fell’ implies one’s position has changed. One can fall from a house and one’s position has changed from being on the house to being on the ground. One who has never been saved position does not change for one who is has always been fallen cannot fall.
John 10:27 show that being of the “them” that shall never perish is CVONDITONAL upon one being a sheep of Christ. One can be a sheep of Christ IF he CONDITIONALLY continues to hear and follow Christ. Therefore being of the “them” that shall not perish is CONDITONAL that one become and remain a sheep of Christ by continuing to hear and follow Christ. The ones that CONDIRONALLY hear and follow Christ are the ones that will not be snatched from God’s hand. Those that quit hearing and following Christ no longer qualify as one of His sheep have removed themselves from God’s hand.