We're not.
Paul isn't teaching anything Jesus didn't teach.
Salvation by faith and the security of the believer.
John 3:14-18 14And as Moses lifted up the serpent in the wilderness, so must the Son of Man be lifted up, 15that whoever believes in him may have eternal life. 16"For God so loved the world, that he gave his only Son, that whoever believes in him should not perish but have eternal life. 17For God did not send his Son into the world to condemn the world, but in order that the world might be saved through him. 18 Whoever believes in him is not condemned, but whoever does not believe is condemned already, because he has not believed in the name of the only Son of God.
John 5:24 Truly, truly, I say to you, whoever hears my word and believes him who sent me has eternal life. He does not come into judgment, but has passed from death to life.
John 6:28-29 28Then they said to him, "What must we do, to be doing the works of God?" 29Jesus answered them, "This is the work of God, that you believe in him whom he has sent."
John 6:35 Jesus said to them, "I am the bread of life; whoever comes to me shall not hunger, and whoever believes in me shall never thirst.
John 6:39-40 39And this is the will of him who sent me, that I should lose nothing of all that he has given me, but raise it up on the last day. For this is the will of my Father, that everyone who looks on the Son and believes in him should have eternal life, and I will raise him up on the last day."
John 6:47 Truly, truly, I say to you, whoever believes has eternal life.
John 7:38 Whoever believes in me, as the Scripture has said, 'Out of his heart will flow rivers of living water.'"
John 11:24-26 24 Martha said to him, "I know that he will rise again in the resurrection on the last day." 25Jesus said to her, "I am the resurrection and the life. Whoever believes in me, though he die, yet shall he live, 26and everyone who lives and believes in me shall never die. Do you believe this?"
John 14:12 "Truly, truly, I say to you, whoever believes in me will also do the works that I do; and greater works than these will he do, because I am going to the Father.
Luke 18:9-14 9He also told this parable to some who trusted in themselves that they were righteous, and treated others with contempt: 10"Two men went up into the temple to pray, one a Pharisee and the other a tax collector. 11The Pharisee, standing by himself, prayed thus: 'God, I thank you that I am not like other men, extortioners, unjust, adulterers, or even like this tax collector. 12 I fast twice a week; I give tithes of all that I get.' 13But the tax collector, standing far off, would not even lift up his eyes to heaven, but beat his breast, saying, 'God, be merciful to me, a sinner!' 14I tell you, this man went down to his house justified, rather than the other. For everyone who exalts himself will be humbled, but the one who humbles himself will be exalted."
John 10:27-29 27 My sheep hear my voice, and I know them, and they follow me. 28 I give them eternal life, and they will never perish, and no one will snatch them out of my hand. 29My Father, who has given them to me, is greater than all, and no one is able to snatch them out of the Father’s hand.
John 20:30-31 30 Now Jesus did many other signs in the presence of the disciples, which are not written in this book; 31 but these are written so that you may believe that Jesus is the Christ, the Son of God, and that by believing you may have life in his name.
And we don’t replace the only mediator between God and man with someone else.
1 Corinthians 9: 23All this I do for the sake of the gospel, so that I too may have a share in it. 24* Do you not know that the runners in the stadium all run in the race, but only one wins the prize? Run so as to win.p 25Every athlete exercises discipline in every way. They do it to win a perishable crown, but we an imperishable one.q 26Thus I do not run aimlessly; I do not fight as if I were shadowboxing. 27No, I drive my body and train it, for fear that, after having preached to others, I myself should be disqualified.
Oh dear, does Paul say that you must work for your salvation and that you can be disqualified? Are the crowns that the yahoos preach about perishable? Is this little passage able to qualify for Protestant inclusion in doctrine?
If you do not persevere until the end you will be disqualified.