Romans 1 has nothing to do with Christians, but with the nation of Israel.
No.
These comments are being made in general in reference to all from the beginning of creation until the time in which Paul is speaking.
For I am not ashamed of the gospel of Christ: for it is the power of God unto salvation to every one that believeth; to the Jew first, and also to the Greek. For therein is the righteousness of God revealed from faith to faith: as it is written, The just shall live by faith. For the wrath of God is revealed from heaven against all ungodliness and unrighteousness of men, who hold the truth in unrighteousness;
Because that which may be known of God is manifest in them; for God hath shewed it unto them. For the invisible things of him from the creation of the world are clearly seen, being understood by the things that are made, even his eternal power and Godhead; so that they are without excuse:
(Rom 1:16-20 KJV)
The clause "Are clearly seen,
being understood by the things that are made, even his eternal power and Godhead; so that they are without excuse" is being spoken in the present tense. To this day it applies.
Romans 11:7, 11-13, 20-21, 25 show the passage is referring to a NATIONAL salvation, not INDIVIDUAL. The passage is talking about the nation of Israel chose to reject God, so God turned to the Gentile nations instead.
It is being spoken corporately but is based on individuals.
But Paul warns that the Gentile nations will be cast off if they choose to reject BELIEVING in God for salvation. Never said they have to maintain works to keep their salvation.
Rom 11:23 And they also, if they abide not still in unbelief, shall be graffed in: for God is able to graff them in again.
The Greek word that is translated unbelief in verse 23 implies disobedience. Here is part of Bauer had to say i relation to the the word in his work....
1)
Unwillingness to commit oneself to another or respond positively to the other’s words or actions, lack of belief, unbelief (Mitt-Wilck. I/2, 155, 11; Jos., Ant. 2, 327; 19, 127) in our lit. always with God or divine action as referent (cp. Cercidas Iamb. [III B.C.], fgm. 18 II, 8 Coll. Alex. p. 217 [=Anon. in turpilucrum 74: AnthLG, Diehl3 fasc.3=Knox 1929 p. 234]; Plut., Coriol. 232 [38, 4], Alex. 706 [75, 2] ἀ. πρὸς τὰ θεῖα καὶ καταφρόνησις αὐτῶν, De Superstit. 2 p. 165b; Ael. Aristid. 47, 66 K.=23 p. 462 D.; Philo, Leg. ad Gai. 118 ἀ. πρὸς τὸν τοῦ κόσμου παντὸς εὐεργέτην [w. ἀχαριστία], Mut. Nom. 201 al.; Jos., Ant. 10, 142). As response to Jesus by inhabitants of Nazareth Mt 13:58; Mk 6:6; a parent of a possessed pers. 9:24; disciples Mt 17:20 v.l. (for ὀλιγοπιστίαν); of some Judeans [ἀ]π̣ιστεί̣[α] PEg2 19; of Israelites toward God Ro 11:20 (τῇ ἀπιστίᾳ=because of their unbelief; ACharue, L’Incrédulité des Juifs dans le NT 1929; on the dat. of cause Schmid III 57; IV 59; M. Ant. 3, 1; ins in ENachmanson, Eranos 11, 1911, 220–25), 23; Hb 3:19. διακρίνεσθαι τῇ ἀπιστίᾳ waver in disbelief Ro 4:20. ἐποίησα ἐν ἀ. while I was still an unbeliever 1 Ti 1:13. καρδία πονηρὰ ἀπιστίας an evil, unbelieving heart Hb 3:12 (on the gen. s. Mlt. 74).—Among Christians w. διψυχία 2 Cl 19:2; w. ἀνομία GJs 20:1 (not pap). Personif. as one of the chief sins Hs 9, 15, 3. (Opp. πίστις) IEph 8:2.—As a characteristic of this age (w. ἀνομία) ending of Mark (16:14) in the Freer Ms. ln. 2.
2)
lack of commitment to a relationship or pledge, unfaithfulness (X., An. 3, 2, 4 et al.; UPZ 18, 5 [163 B.C.]; Wsd 14:25; Philo, Spec. Leg. 2, 8, Decal. 172; Jos., Ant. 14, 349) Ro 3:3 (JGriffiths, ET 53, ’41, 118).—M-M. TW.
Couple that with context and other words used.
For I would not, brethren, that ye should be ignorant of this mystery, lest ye should be wise in your own conceits; that blindness in part is happened to Israel, until the fulness of the Gentiles be come in. And so all Israel shall be saved: as it is written, There shall come out of Sion the Deliverer, and
shall turn away ungodliness from Jacob: For this is my covenant unto them, when
I shall take away their sins. As concerning the gospel, they are enemies for your sakes: but as touching the election, they are beloved for the fathers' sakes. For the gifts and calling of God are without repentance. For as ye in times past have not believed God, yet have now obtained mercy through their unbelief:
(Rom 11:25-30 KJV)
The Gospel; true salvation is to turn from ungodliness through Christ Jesus because He was manifested to take away our sin.
So Say not in thine heart, Who shall ascend into heaven? (that is, to bring Christ (the word; The commandments; the Law) down from above: ) Or, Who shall descend into the deep? (that is, to bring up Christ (the word; The commandments; the Law) again from the dead.) But what saith it? The word (Christ; the Law; The Commandments) is nigh thee, even in thy mouth, and in thy heart (and in thy mind): that is, the word of faith, which we preach;
For Christ (the word; the Law; The Commandments in our hearts; minds and mouths) is the end of the law (written with ink and on tables of stone) for righteousness to every one that believeth.
(Rom 10:6-8; 10:4 )
Incidentally Unbelief in verse 11:30 is translated from a different Greek word. Here is what the BDAG cited...
ἀπείθεια, ας, ἡ (s. ἀπειθής; X., Mem. 3, 5, 5 et al.; ins; pap; 4 Macc 8:9, 18: 12:4; PsSol 17:20)
disobedience, in our lit. always of disob. toward God (cp. Jos., Ant. 3, 316); somet. w. the connotation of disbelief in the Christian gospel (see ἀπειθέω). Those who oppose God are called υἱοὶ τῆς ἀ. Eph 2:2; 5:6; Col 3:6 (some mss. om.; s. KKuhn, NTS 7, ’61, 339 for Qumran parallels).
Of disob. of Israelites Ro 11:30; Hb 4:6, 11; of all humanity Ro 11:32. Personified Hs 9, 15, 3.—DELG s.v. πείθομαι. M-M. TW.
It has always been an issue in regards to disobedience. And it has always been an issue of us refusing the Cure; the indwelling of our LORD GOD in our hearts directing our path through Jesus Christ. Have you not read.....
And the LORD thy God will circumcise thine heart,
the circumcision made without hands, in putting off the body of the sins of the flesh by the circumcision of the Christ;
If thou shalt hearken unto the voice of the LORD thy God, to keep his commandments and his statutes which are written in this book of the law, and if thou turn unto the LORD thy God with all thine heart, and with all thy soul. For this commandment (hearkening unto the LORD to keep his commandments and his statutes which are written in this book of the law) which I command thee this day, it is not hidden from thee, neither is it far off. It is not in heaven, that thou shouldest say, Who shall go up for us to heaven, and bring it unto us, that we may hear it, and do it? Neither is it beyond the sea, that thou shouldest say, Who shall go over the sea for us, and bring it unto us, that we may hear it, and do it? But the word (Christ; his commandments and his statutes which are written in the book of the law) the is very nigh unto thee, in thy mouth, and in thy heart, that thou mayest do it. The epistle of Christ; written not with ink, but with the Spirit of the living God; not in tables of stone, but in fleshy tables of the heart. And such trust have we through Christ to God-ward: Not that we are sufficient of ourselves to think any thing as of ourselves; but our sufficiency is of God; For it is GOD that works in us both to will and do HIS good pleasure.
(Deu 30:6; Col2:11; Deu 30:10-14; 2Co 3:3-5 )