Salvation is eternal but no verse says one has UNCONDITIONAL eternal salvation. A Christian can fall away, become an apostate therefore no longer has the promise of eternal salvation.
Jude commands the Christian to keep yourselves in the love of God which implies the Christian can fall out of God’s saving, gracious love and become lost. Both Jude and James shows the Christian does have both ability and responsibility to “keep themselves” as to not fall away.
IF eternal security were true, then Charles Stanley would be right in that one could be saved without faith and be saved while not being a disciple of Christ but Stanley’s position is completely against NT teaching
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