Okay, let's see here...
1) I always like how I'm expected to provide exact citations and excerpts to support my position (which I have), but these just-so platitudes about "what the Bible teaches" and "what Paul teaches" are presented as if they are sufficient in and of themselves. Sorry, I ain't buyin' it.
2) A "simple belief and acceptance of Jesus' Death and Resurection" is indeed what I would describe to be an intellectual and emotional commitment to a set of metaphysical beliefs. It is also at odds with the Pauline injunction to experience a mystical death and resurrection themselves, go beyond "elementary teachings", and become transfigured "in Christ's likeness". The fundamental difference is that the paradigm you are positing is entirely intellectual in nature, requiring a simple modification of one's beliefs and opinions about the world (in other words, translative religion). The Pauline epistles themselves refer to his as a "psychic" level of understanding (connoting to an understanding involving the psyche or mind). The genuine Pauline injunction, by contrast, is mystical and experiential in nature, requring an actual transformation on the part of the individual self-system (in other words, transformative religion). The Pauline epistles refer to this as a "pneumatic" level of understanding (connoting to an understanding involving the pneuma or spirit).
3) While you may not like actual excerpts from the source material and prefer fallacious Appeals To Belief, you'll just have to indulge me momentarily:
"The psychic does not receive the things of the Spirit of God; they are foolishness to him; he cannot recognize them, because they are pneumatically discerned, but the pneumatic discerns all things." (1 Corinthians 2:14-15)
"And I, brothers, was not able to speak to you as pneumatics, but as to sarkics --- as to those uninitiated in Christ. I fed you milk, not meat, for you were not yet ready for it. Nor are you now. You are still sarkic. For where there is strife and envy among you, are you not sarkic? Are you not acting like mere men?" (1 Corinthians 3:1-3)
"Therefore let us leave behind the elementary teachings about Christ and go on to another level of initiation (ten teleioteta), not laying again the foundation of repentance from dead works and of faith in God, instruction about baptisms, the laying on of hands, the resurrection of the dead, and eternal judgment. And God permitting, we will do so.
For it is impossible for those who have been enlightened, who have tasted the heavenly gift, who have shared in the Holy Spirit, who have tasted the goodness of God's Word (Logos) and the powers of the coming age, to have fallen back to renew repentance again. They re-crucify for themselves the Son of God." (Hebrews 6:1-6)
"Flesh and blood cannot inherit the kingdom of God, nor does the perishable inherit the imperishable". (1 Corinthians 15:50)
"This is it: the duly appointed time! This is it: the day of salvation." (2 Corinthians 6:2)
"But because of his great love for us, God, who is rich in mercy, made us alive with Christ even when we were dead in transgressions --- it is by grace you have been saved. And God raised us up with Christ and seated us with him in the heavenly realms in Christ Jesus, in order that in the coming ages he might show the incomparable riches of his grace, expressed in his kindness to us in Christ Jesus." (Ephesians 2:4-7)
"Or don't you know that all of us who were baptized into Christ Jesus were baptized into his death? We were therefore buried with him through baptism into death in order that, just as Christ was raised from the dead through the glory of the Father, we too may live a new life. If we have been united with him like this in his death, we will certainly also be united with him in his resurrection. For we know that our old self was crucified with him so that the body of sin might be done away with, that we should no longer be slaves to sin --- because anyone who has died has been freed from sin." (Romans 6:3-7)
"I have become [the church's] servant by the commission God gave me to present to you God's Word (Logos) in its fullness --- the mystery that has been kept hidden for ages and generations, but is now disclosed to the saints. To them God has chosen to make known among the Gentiles the glorious riches of this mystery, which is Christ in you, the hope of glory." (Colossians 1:25-27)
"But if Christ is in you, your body is dead because of sin, yet your spirit is alive because of righteousness. And if the Spirit of him who raised Jesus from the dead is living in you, he who raised Christ from the dead will also give life to your mortal bodies through his Spirit, who lives in you." (Romans 8:10-11)
"I want to know Christ and the power of his resurrection and the fellowship of sharing in his sufferings, becoming like him in his death, and so, somehow, to attain to the resurrection from the dead." (Philippians 3:10-11)
"I have been crucified with Christ and I no longer live, but Christ lives in me." (Galatians 2:20)
"Now the Lord is the Spirit, and where the Spirit of the Lord is, there is freedom. And we, who with unveiled faces all contemplate the Lord's glory, are being transfigured into his likeness, from splendor to splendor, which comes from the Lord, who is the Spirit." (2 Corinthians 3:17-18)
"For the logos (word) of God is living and active. Sharper than any double-edged sword, it penetrates even to dividing psyche (mind) and pneuma (spirit), joints and marrow; it judges the heart and attitudes of the heart." (Hebrews 4:12)
I read the Pauline authors talking about knowing "the fullness of God's Word" which is "Christ in you", going beyond "elementary teachings" to a "new level of initiaton", "dividing mind and spirit", becoming transfigured into Christ's likeness "splendor to splendor", being raised "up with Christ" and seated "with him in the heavenly realms in Christ Jesus", and being "crucified with Christ" so that "I no longer live, but Christ lives in me".
I am reading nothing, however, in all of that of Paul saying "simply believing what I'm saying is good enough!". In fact, he very explicitly distinguishes between different levels --- sarkic, psychic, pneumatic --- of understanding.
Sorry, I'm not buyin' it.
4) The problem here is that the only Christians to use the Pauline epistles as an authority prior to Irenaeus are heretics like Marcion and Valentinus. Justin Martyr is completely ignorant of Paul and never quotes him. Furthermore, literalists like Irenaeus only use the Pauline epistles alongside the forged Pastoral Letters (which Irenaeus himself may have very well written), never beforehand.
5) As for evidence, I would suggest (among others) G. Ludemann's Heretics, which states: "Scholars generally agree that of the thirteen extant letters, seven are authentic (Romans, 1 and 2 Corinthians, Galatians, Philippians, 1 Thessalonians, and Philemon), whereas the rest have been composed by later disciples in the apostle's name." In his Did Jesus Exist?, G. A. Wells refers to Schimthal's evidence that all the principal Pauline letters, apart from Galatians, are likewise composite works. E. Pagels, in The Gnostic Paul, also provides evidence that early Church fathers like Irenaeus and Tertullian were not above tampering with Paul's letters to make a theological point to their readers (in one of the examples she gives, the fathers quote from Galatians but omit the word 'not' from a key passage).
6) G. Ludemann writes of the Pastorals: "The consensus among scholars today is that the historical Paul cannot be the author of the Pastorals, either directly or indirectly." He also writes: "In terms of the history of the canon, [the Pastoral Letters] are attested only relatively late, but always as a unity. Irenaeus (190 CE) is the first to know and use them. Indeed the very title of his work against heretics, Unmasking and Refutation of the Gnosis, Falsely So-Called, leans explicitly on 1 Timothy 6:20." The Pastoral Letters and the Acts of the Apostles are both unknown to Justin Martyr, Valentinus, and Marcion --- all of whom lived a mere generation earlier than Irenaeus.
7) The Apostolic Letters attributed to Peter, James, and John are not very well-supported by modern scholarship, either. A. Gaus, in The Unvarnished New Testament, writes of 2 Peter: "It refers to the apostles as 'our ancestors' as if they were dead and buried." I. Wilson, in Jesus: The Evidence, provides evidence that 1 and 2 Peter were forged in Peter's name in the third century to give an appearance of amity between Peter and Paul, even though they are described as at odds in the Pauline epistles, writing of "our brother Paul [...] so dear to us" (2 Peter 3:15). The Church historian Eusebius (circa 300 CE) regarded the epistles of James, Jude, 2 Peter and 2 and 3 John as disputed books. Didymus in 398 CE declared 2 Peter to be a forgery. G. A. Wells demonstrated that all these Apostolic Letters took a very long time to become part of the established canon of the New Testament.
Laterz.