Knowing you as best I do, I doubt that you have ever claimed that your ability to quote Scripture can save you, so you should state that his "Scripture saves" tangent is a straw man argument, then I would stick with Scripture as deeply into the discussion as you can. Only after they have been beaten by Scripture into accepting Tradition can you use the Fathers and Magisterium against their ʝʊdɛօ-Protestant heresies.
Worth noting by "Bible Believers" who reject God's judgment regarding His Church when he spoke to the 72 disciples:
"He that heareth you, heareth me; and he that despiseth you, despiseth me; and he that despiseth me, despiseth him that sent me." Luke 10:16 …then you can cite the Scripture showing thta God invested Peter with the authority to govern (Matthew 16:19 & 18:18), teach (Matthew 28:19-20), and sanctify (Matthew 28:18-19; John 20:23). Divinely and logically consistent with His commissions, Jesus founded one Church, singular, with one central authority (Matthew 16:19 & 18:18), a visible organized society (Mark 4:11), and called for oneness of doctrine (John 17:11, 21-23).
Worth noting by "Bible Believers" who think the unbaptised have a normative path to Heaven:
"He that believeth and is baptized, shall be saved: but he that believeth not shall be condemned." Mark 16:16
Of course, you will need to point out that the verse does not read "only faith" and adduce the three dozen verses that teach good acts are necessary for salvation.
You can point out the absolute necessity of receiving the true sacramental Body and Blood of Jesus Christ:
"Then Jesus said to them: Amen, amen I say unto you [a marker for a teaching that must be taken literally]: Except you eat the flesh of the Son of man, and drink his blood, you shall not have life in you. He that eateth my flesh, and drinketh my blood, hath everlasting life: and I will raise him up in the last day." John 6:54-55
“And he is the head of the body, the church, who is the beginning, the firstborn from the dead; that in all things he may hold the primacy:…” Colossians 1:18
“And he said to them: Go ye into the whole world, and preach the gospel to every creature. He that believeth and is baptized, shall be saved: but he that believeth not shall be condemned.” Mark 16:15-16
“Being subject one to another, in the fear of Christ. Let women be subject to their husbands, as to the Lord: Because the husband is the head of the wife, as Christ is the head of the church. He is the saviour of his body. Therefore as the church is subject to Christ, so also let the wives be to their husbands in all things. Husbands, love your wives, as Christ also loved the church, and delivered himself up for it: That he might sanctify it, cleansing it by the laver of water in the word of life: That he might present it to himself a glorious church, not having spot or wrinkle, or any such thing; but that it should be holy, and without blemish. So also ought men to love their wives as their own bodies. He that loveth his wife, loveth himself. For no man ever hated his own flesh; but nourisheth and cherisheth it, as also Christ doth the church: Because we are members of his body, of his flesh, and of his bones.” Ephesians 5:21-30
“But if I tarry long, that thou mayest know how thou oughtest to behave thyself in the house of God, which is the church of the living God, the pillar and ground of the truth.” 1 Timothy 3:15
“And I say to thee: That thou art Peter; and upon this rock I will build my church, and the gates of hell shall not prevail against it. [19] And I will give to thee the keys of the kingdom of heaven. And whatsoever thou shalt bind upon earth, it shall be bound also in heaven: and whatsoever thou shalt loose upon earth, it shall be loosed also in heaven.” Matthew 16:18-19
“Let us be glad and rejoice, and give glory to him; for the marriage of the Lamb is come, and his wife [The Church is the Bride of Christ] hath prepared herself.” Apocalypse (Revelation) 19:7
“He that heareth you, heareth me; and he that despiseth you, despiseth me; and he that despiseth me, despiseth him that sent me.” Luke 10:16
“Not forsaking our assembly, as some are accustomed; but comforting one another, and so much the more as you see the day approaching. For if we sin willfully after having the knowledge of the truth, there is now left no sacrifice for sins, But a certain dreadful expectation of judgment, and the rage of a fire which shall consume the adversaries.” Hebrews 10:25-27 [Commentary from the Douay-Rheims translation: “If we sin willfully”: He speaks of the sin of willful apostasy from the known truth; after which, as we can not be baptized again, we can not expect to have that abundant remission of sins, which Christ purchased by his death, applied to our souls in that ample manner as it is in baptism: but we have rather all manner of reason to look for a dreadful judgment; the more because apostates from the known truth, seldom or never have the grace to return to it.”]
“Then Jesus said to them: Amen, amen I say unto you [a marker for a teachung that must be understood literally]: Except you eat the flesh of the Son of man, and drink his blood, you shall not have life in you. He that eateth my flesh, and drinketh my blood, hath everlasting life: and I will raise him up in the last day.” John 6:54-55 His Body and Blood is available only in His Church.
“And taking bread, he gave thanks, and brake; and gave to them, saying: This is my body, which is given for you. Do this for a commemoration of me. In like manner the chalice also, after he had supped, saying: This is the chalice, the new testament in my blood, which shall be shed for you.” Luke 22:19-20 His Body and Blood is available only in His Church. [Commentary from the Douay-Rheims translation: “Do this for a commemoration of me”: This sacrifice and sacrament is to be continued in the church, to the end of the world, to shew forth the death of Christ, until he cometh. But this commemoration, or remembrance, is by no means inconsistent with the real presence of his body and blood, under these sacramental veils, which represent his death; on the contrary, it is the manner that he himself hath commanded, of commemorating and celebrating his death, by offering in sacrifice, and receiving in the sacrament, that body and blood by which we were redeemed.]