“Now I am making known to you, brethren, the good news which I bring to you, which also you accepted, in which also you stand, through which also you are saved, if you are retaining what I said in bringing the good news to you, unless you did not actually believe. For I give over to you among the first what also I accepted, that Christ died for our sins according to the scriptures, and that He was entombed, and that He was resurrected on the third day according to the scriptures.” (1 Corinthians 15:1-4).
The fact that Christ died, was entombed and then resurrected on the third day is what saves humanity. Our faith in the good news is a "gift" from God - salvation is by the grace of God.
"For in grace, through faith, are you saved, and this not out of you; it is God's approach present, not of works, lest anyone should be boasting." (Ephesians 2:8-10)
God's "mercy" and the "transcendent riches of His grace" will be displayed in humanity in the ages to come.
"God, being rich in mercy, because of His vast love with which He loves us (we also being dead to the offenses and the lusts), vivifies us together in Christ (in grace are you saved!) and resurrects us together and seats us together among the Celestials, in Christ Jesus, that, in the oncoming ages, He should be displaying the transcendent riches of His grace in His kindness to us in Christ Jesus." (Ephesians 2:4-7)
"...through Him to reconcile all to Him, whether those on the earth or those in the heavens." (Colossians 1:20)
Humanity is destined to have a seat "among the Celestials" where they will display "the transcendent riches of His grace in His kindness to us in Christ Jesus".
So, the result of the gospel of grace in a nutshell - we're all in!
"...we have hope in the living God, who is the Savior of all humanity, especially of believers. These things be charging and teaching." (1Timothy 4:10)
"For the grace of God has appeared, bringing salvation to everyone." (Titus 2:9)