In Christianity a "Saved" person can become not "Saved"

When ever discussing the topic of salvation, there are 2 things that must be understood. The Law, and the Gospel.If a person doesn't not have a full understanding of these 2, conclusions like losing salvation will be a possibility.The LawMost of us should be familiar with the 10 commandments, and quite a few people believe that they can uphold them. However, I am only going to use the 2 greatest commandments to help me explain the extent of the Law.Matthew 22:37-4037 Jesus replied: “‘Love the Lord your God with all your heart and with all your soul and with all your mind.’ 38 This is the first and greatest commandment. 39 And the second is like it: ‘Love your neighbor as yourself.’ 40 All the Law and the Prophets hang on these two commandments.Why do they all hang on these two?Because the Law is spiritual, and if you love God with all your heart, soul, and mind, you will uphold the all of the commandments perfectly. The heart is where we are judged first under the Law, not the actions that follow. Now you may ask, does one need to obey them all "perfectly"?Yes:Matt. 5:4848 Be perfect, therefore, as your heavenly Father is perfectThe Law requires perfect righteousness, requires that you obey willingly, and requires that you love to do it, for your entire life. If you haven't figured it out by now, this is bad news. None of us follow the 2 greatest commandments, therefore, we break them all; everyday, all day. Our heartsJeremiah 7:99 The heart is deceitful above all thingsand beyond cure.Who can understand it?No one is righteous, understands, or seeks GodRomans 3:10-1210 As it is written: “There is no one righteous, not even one;11 there is no one who understands;there is no one who seeks God.12 All have turned away,they have together become worthless;there is no one who does good,not even one.” So we have it very clearly established, that no one can uphold the Law, and if we are subject to judgement based on our hearts or actions- we are doomed. The GospelThis is the Good news, and after that last bit, it's much needed. God is very well aware of our depravity, and knows us full an well, since before we were created, and far after we die. Surely he knew we would fail, and thanks be to him, he created an alternative; or was it always meant to be this way?Enter Christ.John 3:16 16 For God so loved the world that he gave his one and only Son, that whoever believes in him shall not perish but have eternal life. Simple.. live under the Law and surely die, or trust in Christ and receive eternal life.Of course this is a very dumbed down version, but it is very important to emphasize on the essential factor, which is:Faith in Christ = SalvationThe topic at handThis is where it gets fun.My opponent will have you believe, that along with belief, there is a list of other conditions that need to be met and complied with, in order to be saved; salvation is never sure. Now, per john 3:16, how can he assert such a thing?He posts: Mark 13:13 [Jesus said] “All men will hate you because of me, but he who stands firm to the end will be saved.” [NIV] If we take this at face value, it's an apparent contradiction. Since we are debating the issue of salvation, we must hold that the Bible is infallible, and cannot contain such errors(which I personally believe as well). For this, we must find something solid, something that cannot be reasonably interpreted any other way. I go to Ephesians:4 For he[God] chose us in him[Christ] before the creation of the world to be holy and blameless in his sight(1). In love 5 he predestined us for adoption to sonship through Jesus Christ, in accordance with his pleasure and will— 6 to the praise of his glorious grace, which he has freely given us in the One he loves. 7In him we have redemption through his blood, the forgiveness of sins, in accordance with the riches of God’s grace 8 that he lavished on us. With all wisdom and understanding, 9 he made known to us the mystery of his will according to his good pleasure, which he purposed in Christ, 10 to be put into effect when the times reach their fulfillment —to bring unity to all things in heaven and on earth under Christ.(2) 1) This very clearly says, that before creation, God chose whom he would save through Christ. It also says, that those who were chosen in Christ, would be holy and blameless in his sight; we would not be held accountable for our sinful lives. He goes on to say, that this gift of salvation, was given to us freely; we did not earn it or maintain it. 2) With all wisdom and understanding. This says to me, that he knew we would all be unrighteous, and saved us anyways. He purposed this in Christ, meaning: It was always Christ who was to bring him pleasure, and all of us chosen in him he would be pleased with, because of Christ, not because of ourselves. When my opponent expounds on the "stand firm until the end", he seems to imply something we must do, however, the passage from Ephesians seems to imply otherwise; God predestined his chosen to stand firm, because he placed belief in them. The passage from Matthew was not of uncertainty as to who will stand firm, and who won't, it was declaring very clearly, that those who are saved, will have no choice but to stand firm, because God chose them. Matthew 10:33 “But whosoever shall deny me before men, him will I also deny before my Father which is in heaven.” (KJV) For this passage I must ask my opponent:Was the apostle Peter a case of last salvation, since he denied Christ 3 times before men?Or does this mean, those who've denied him, were never meant to be saved, and never confessed Christ to begin with.1 John 2:18-1918 Dear children, this is the last hour; and as you have heard that the antichrist is coming, even now many antichrists have come. This is how we know it is the last hour. 19 They went out from us, but they did not really belong to us. For if they had belonged to us, they would have remained with us; but their going showed that none of them belonged to us. Also, since I hold to our total depravity, I believe we will stumble and fall, time and time again, which is a testament to the grace of God and his promise to save those he's chosen to have faith:2 Timothy 2:1313 If we are faithless, He remains faithful, for He cannot deny Himself.Once saved, always savedThis brings me to my conclusion, which by now should be clear. We were predestined to be saved, by God, through Christ, NOT of ourselves. Since we have been removed from the equation, there is no sense in believing that we can some how lose our salvation due to actions or sin. We will never lose our salvation because we were chosen outside of ourselves, and since this is God's method of election, we cannot remove ourselves from his hand.Romans 911 Yet, before the twins were born or had done anything good or bad —in order that God’s purpose in election might stand: 12 not by works but by him who calls—she was told, “The older will serve the younger.” 13 Just as it is written: “Jacob I loved, but Esau I hated.”Here once again, we see that God keeps the power to save, and that he wished for us to understand, that salvation is his gift to us. Not a reward of dedication or obedience.continued... 14 What then shall we say? Is God unjust? Not at all! 15 For he says to Moses, “I will have mercy on whom I have mercy,and I will have compassion on whom I have compassion.” 16 It does not, therefore, depend on human desire or effort, but on God’s mercy. So be thankful sinners! You salvation is sure, and you can now rejoice knowing that Christ has paid the price- in full. So that you, his elect, may have eternal life. Back to you Pro.