Moreover whom he did predestinate, them he also called: and whom he called, them he also justified: and whom he justified, them he also glorified.
This verse tells us that from the moment God chooses us, it is as if we are glorified in His presence in heaven already. Notice that Paul writes here in the past tense… so certain that these things will be done, he writes as though they have already been done. Also, note that every person that gets predestinated also gets called, and everyone who gets predestinated also gets justified, and everyone who gets justified also gets glorified. There are no 'drop-outs'; no one gets lost along the way.
This is very consistent with John 6:35-40. What's striking, actually, is that because there is such consistency regarding the eternal security of the believer, it really is rather easy to make the case. There is that much support for it, and from so many different angles.