Lots of people have wondered about this, sometimes long after they have believed, especially after a moment of personal weakness or a particularly rough patch in life's walk.  Sometimes the person looks back at their personal experience and holds the current crisis up as a counterpoint. For example: I sin today and think "Am I still saved? Especially in light of me trusting God to save me twenty two years ago? Especially in light of me preaching for years?"

We think about time as a series of points: anything before a certain point is not included in that time interval. My trip from New York to Florida is measured in miles from where I parked my car to where I stopped it—but it doesn't include me dragging luggage down the stairs.

But God doesn't look at time that way. Concerning those who are labeled the Called (that being someone who has heard the Gospel, believed it and trusted) are labeled as Predestinated, Justified, Sanctified and Glorified. Those same people we're told that nothing can separate them from God's love; not death, or torture or demons or even angels. We're told that God is altogether on the side of those people: the Father who can bring the charge, justifies them; the Spirit who is in the Godhead dwells within them reworking them and helping them; the Son who can condemn intercedes on their behalf.

So God in all three persons seems to be saying He's dedicated to this course of action for these people and He will ultimately complete it. Paul says it this way "He who has started a good work in you will ultimately complete it in the day of Jesus Christ" (Phil 1:6).

But that's all well and good for people who are loving God and not going through an incredibly faith-shaking time or have fallen into the grossest of sin—but what about us who have messed up to the point that we are drowning in it? Are those of us unsaved: we had it but we lost it?

This is important: God alone saves. Our prayers didn't save us. Our baptism didn't save us. Our confession didn't save us. Heck, our belief didn't save us: God saved us. The fact that He specified our rather pitiful belief on His Perfect Son as the vehicle by which He would funnel salvation is altogether God's decision in showing mercy.

So then Paul points out that those who are saved can exult, that is be firmly convinced and joyfully expectant, in our tribulations/tests/trials knowing that the goal is to bring about perseverance or endurance and that is to bring about a perfected character and that a non-disappointing hope or watchful expectancy. In other words, the believer should expect that the rough times he or she is going through are meant to keep him or her in the faith, yield results in character that prepare for further rough patches.

"But what if I mess up?"

Like David? Who was, definitely saved before he seriously messed up and slept with Bathsheba? Or like Abraham, who was definitely saved before he lied in Egypt or even again, years later, in Gerar? Or like Peter, who was definitely saved before he up and denied the Lord three times? Or like Lot whose life in Sodom left him doing horrid things but Peter describes as righteous?

We will mess up but our ultimate salvation from God's wrath isn't based on our mess ups or our doing alright. The Gospel was meant for Messed Up People.

Hold on to this: If God was willing to send His Son to die for you while you were still a sinner how much more is He willing to ensure your salvation now that you have believed?

That section where Paul is talking about the use of tribulations (Romans 5), Paul begins with: "Therefore, having been justified by faith, we have peace with God through our Lord Jesus Christ."

Before placing trust on Jesus Christ we were enemies of God—recipients of His due wrath but after (still thinking linearly) we have an end of hostilities and all the benefits of being on the same side. That means end of hostilities as well as the overwhelming benefits from being on the same side. Hostilities ended on account of His Son Jesus Christ and hostilities not to start up again on the same grounds.

That means that although there are times where a true believer can so mess up that they can doubt their salvation they are still under God's peace. That means that since God isn't constrained to linear thinking He can say things like "you have an end goal, you have responded to my calling, you have been declared not-guilty, you have been made clean, you have been made gloriously perfect: the triune God is altogether on your side".

It is important that we recognize in ourselves the capability to constantly mess up and also truly, honestly, examine if we really ever trusted the Lord to begin with. Not in such a manner that we throw away our faith (and thus prove that we never really believed Him like those in John 8) but in such a manner where we soberly look at our current mistakes and really hold them up to God's Gospel.

His Gospel is this: that God had the authority and right to pour down wrath on his rebellious creation (Rom 1-3)  but He showed mercy to all of them (Rom 9: for all of them have sinned (Rom 1-3, Rom 11)) by sending His Son to take their punishment (Rom 3}) that whoever believed on His Son ({{Rom 3-4), confessed Him as the Lord God, trusted on Him as the only means of salvation and believed that He rose from the grave God (Rom 10) would justify(Rom 5), later save from His just wrath and currently save us from the bondage to our sin(Rom 6), would continue to work in the believer(Rom 8), perfecting them (as they perfect themselves knowing that they would mess up—Romans7) so that at the end they will be presented Perfect before God (unlike their previous state). So then in this current world, the believer will struggle (Rom 7) but he stands on equal footing with all people knowing that he/she lives by God's mercy so now they can exemplify that to other people and reflect God's goodness, peace and mercy towards all people (Rom 13-16) not repaying evil for evil but making room for God to work (Rom 12).

So can a person that God saved become unsaved? Never—God has saved them and nothing can remove them from God's hands. So can a person who has confessed Jesus as Lord and Savior, or responded to the altar call, or been baptized lose their salvation? Those things are not the things that saved us so it is possible for a person to never truly have believed and to rely on them for salvation. So how does a person know that they are saved? By reexamining themselves in light of God's Gospel and understanding that what He says is true—those who rely on the power and authority of the Lord God  Jesus the Christ and believe that He rose from the grave will be undeniably saved.