God’s elect will not lose their salvation because God’s sovereign, decretive will perseveres the faith of his people.
The eschatological warnings for believers not to apostatize function as a means by which God perseveres his people to the end.
This topic often comes up in eschatological discussions (e.g. Can a true believer take the mark and still be saved? Answer: No believer will take the mark, since his overcoming faith will not allow him.)
For an excellent study on this topic and key texts, here is Apostasy and Perseverance by Steve Hays:
Be sure to check out the extensive bibliography in his book for further reading.