This occurs in a time to come, when the judgement of Israel and the Nations have taken place during the seven year tribulation. Christians need not fear; we await for Christ who will come in the clouds for His Church, when all who are born again are taken to be with him (1 Thes 4:13-18).

However, of importance is the means of salvation - it's by the blood of Christ, shed on the cross, that saves - shed because of the love of Christ for us; and thus it's by grace we are saved (Ephesians 2:8).  However, you need to have faith in Jesus Christ (John 3:16) which means believing with your heart  that Christ is the Son of God, (and obviously confessing what you are believing, with your mouth - one without the other is empty faith, or faith through osmosis, or more rightly faith in faith which has no effect).

It’s like kicking a ball towards a goal – without the ball (the confession) your kick is absolutely meaningless. Yes, faith is a work and totally in tune with God’s councils; we can only have faith because of His great grace; without His grace, we could not possibly have faith. Its grace (the work of the Lord Jesus Christ) that saves; but to assimilate this grace – that is, to have it apply to you, you need to believe (a specific action by you) that the Lord Jesus Christ is the Son of God (John 3:16). The Holy Spirit provides the means for this to occur.

Note some ill-informed Christians take umbrage to the fact that the action ‘to believe’ (and thus a work) requires the simultaneous action of heart and mouth – because they are joined and inseparable; being a picture of our conscious decision to accept the truth of a proposition and act upon it (of which the truthfulness and validity the Holy Spirit attests to, in our hearts). The heart believes what our mouth confesses, and our mouth confesses the word what our heart believes (according to Moses and quoted by the Apostle Paul – See Romans 10 and Deut. 30). If this does not occur, there is simply no belief because there is no proposition the heart believes. Some go as far as saying the heart believes, because that’s not a work, which is both false, and illogical – a heart needs to ‘work’ to believe, because ‘to believe’ is an action on the part of the human, requiring expenditure of energy; our consciousness must be alive and operable, else we are brain dead! They then illogically say the mouth cannot confess, because that’s a work, and as such would make you ineligible for salvation (and logically these believe the saving atonement of Christ’s blood is not sufficient for all sins). Further, they falsely stop Christians reading Romans 9-11, saying these verses only applies to Jews, when in fact the Apostle Paul, with all clarity writes:

For there is no distinction between Jew and Greek; for the same Lord is Lord of all, bestowing his riches on all who call on him.  For "everyone who calls on the name of the Lord will be saved." 

[I do note that the place and means of confession is not prescribed – it neither needs to be audible nor before a group of people, although Jewish Christians, such as those the Book of Hebrews is written to, would have done so publically; it became part the mark of their separation from Judaism - for which the writer commends them three times.]