Is Christ's atoning sacrifice for all humanity?
Yes. The offering Christ freely made on the cross is the perfect and sufficient sacrifice for the sins of the whole world.
Catechism for the Global Methodist Church, question 57
3I will bless those who bless you, and the one who curses you I will curse, and in you all the families of the land shall be blessed."
8This is the declaration of the Lord GOD, who gathers the outcasts of Israel: I will gather still more to those already gathered.
29The next day he saw Jesus coming to him and said, "Look, the Lamb of God, the one who takes away the sin of the world."
16For God so loved the world that he gave the unique son, in order that everyone who trusts in him should not perish but have eternal life. 17God did not send the Son into the world to condemn the world, but in order that the world might be saved through him.
24Truly, truly, I say to you that the one who hears my word and believes him who sent me has eternal life and does not come into judgment, but has passed from death to life.
12Again therefore Jesus spoke to them, saying, "I am the light of the world. Whoever follows me will certainly not walk in darkness, but will have the light of life."
25Jesus said to her, "I am the resurrection and the life. The one who trusts in me, even if he dies, will live.
32And I, when I am lifted up from the earth, will draw all to myself."
11If the Spirit of the one who raised Jesus from the dead dwells in you, then the one who raised Christ Jesus from the dead will also give life to your mortal bodies through his Spirit dwelling in you.
14For the love of Christ holds us, because we have judged this: that one died for all; therefore all died. 15And he died for all so that those who live might no longer live for themselves but for him who died and was raised for them.
3This is good and acceptable before God our Savior. 4Who desires all people to be saved and to come to the knowledge of the truth. 5For there is one God, and one mediator between God and men, the man Christ Jesus. 6Who gave himself as a ransom for all: the testimony at the proper times.
9But we see Jesus, who for a little while was made lower than the angels because of the suffering of death, crowned with glory and honor, so that apart from God he might taste death on behalf of everyone.
12But when he had offered for all time a single sacrifice for sins, he sat down at the right hand of God.
9The Lord does not delay the promise, as some count slowness, but has patience toward you, not planning that any should perish but that all should come to repentance.
9If we confess our sins, he is faithful and just to forgive us our sins and cleanse us from all unrighteousness.
2And he himself is the propitiation for our sins, and not for ours only but also for the sins of the whole world.
Christ died for everyone. Article VIII of the Confession of Faith says: "The offering Christ freely made on the cross is the perfect and sufficient sacrifice for the sins of the whole world." ΒΆ102.1 of the Book of Doctrines and Discipline says that the church "celebrates the universal love of God in affirming that Christ died for all people with the result that the gift of salvation is available to all persons." Here Wesleyan theology parts from any doctrine of a limited atonement.
Scripture teaches this universality from the first promise to the last epistles. God told Abraham, "in you all the families of the land shall be blessed" (Genesis 12:3). John the Baptist called Jesus "the Lamb of God, the one who takes away the sin of the world" (John 1:29). Jesus said, (John 3:17), and that when he was lifted up he would "draw all to myself" (John 12:32). Paul writes that "one died for all" (2 Corinthians 5:14) and that Christ "gave himself as a ransom for all" (1 Timothy 2:6). John writes that "he himself is the propitiation for our sins, and not for ours only but also for the sins of the whole world" (1 John 2:2).
The sacrifice is "perfect and sufficient." Christ "had offered for all time a single sacrifice for sins" and then "sat down at the right hand of God" (Hebrews 10:12). No priest and no penitent can add anything to it. It is sufficient for all, and it is received by those who believe; the same chapter of John that says God loved the world also says eternal life belongs to "everyone who trusts in him" (John 3:16).
For a Methodist this doctrine shapes evangelism and pastoral care. The church can say honestly to anyone that Christ died for him. No sin lies outside the reach of the cross, so confession is met with forgiveness and cleansing (1 John 1:9). And no one has ground for despair about his own standing, because the promise is to whoever follows him: (John 8:12).