They do IFF the believer overcomes and endures to the end without wavering, believing and obeying everything the LORD Jesus taught us by his apostles. There is no guarantee of salvation to the reprobate who depart from the faith they once held.
Those verses don’t use future tense, they use past tense.
I am currently seated in the heavenly places IN CHRIST JESUS.
Jesus promised that He would lose none of those whom the Father gave Him.
That verse about enduring to the end is for those in the end, going through the tribulation, not those of the church age. Again, another verse taken out of context.