Their efforts fill them with Christ's grace which alone saves. And the opposite: denial of the Church founded by Christ separates them from His grace.
Wrong.
James 4:6 But he gives more grace. Therefore it says, “God opposes the proud, but gives grace to the humble.”
1 Peter 5:5 Likewise, you who are younger, be subject to the elders. Clothe yourselves, all of you, with humility toward one another, for “God opposes the proud but gives grace to the humble.”
And the opposite: denial of the Church founded by Christ separates them from His grace.
Book, chapter, and verse please.
God gives grace, not the church.
No one here other than Catholics have denied the church founded by Christ. Catholics continually deny that those who have accepted Christ as their savior are part of the church founded by Christ.
The church I belong to is much older than the RCC.
Romans 16:5 Likewise greet the church that is in their house. Salute my well-beloved Epaenetus, who is the firstfruits of Achaia unto Christ.
Colossians 4:15 Salute the brethren which are in Laodicea, and Nymphas, and the church which is in his house.
Philemon 1:2 And to our beloved Apphia, and Archippus our fellowsoldier, and to the church in thy house:
We see the RCC which was established years later this way.
Romans 16:17 Now I beseech you, brethren, mark them which cause divisions and offences contrary to the doctrine which ye have learned; and avoid them. 18 For they that are such serve not our Lord Jesus Christ, but their own belly; and by good words and fair speeches deceive the hearts of the simple.