Wesley saw the Lord's Supper as a means of grace. He describes "means of grace" as outward signs, words, or actions ordained of God, and appointed for this end--to be the ordinary channels whereby he might convey to men and women preventing, justifying, or sanctifying grace ("The Means of Grace," in F. Baker, The Works of John Wesley, vol. 1 [Abingdon, 1984] 385).
Among the other means of grace are prayer, searching the Scriptures, fasting, Christian conferencing, and works of mercy to our neighbor. Some of these involve words, some actions, but the Lord"s Supper integrates all three—signs, words, and actions—into one liturgical event. Is it any wonder that C. Wesley can call the Lord's Supper God's "choicest instrument" through which all of God's blessings are given (J. Rattenbury, The Eucharist Hymns of John and Charles Wesley [Epworth, 1948] 208)?
The central point of this definition is the purpose of the means of grace: they are ordinary channels of God's grace. While God can and does act graciously in extraordinary ways, we are called to regularly meet God in the ordinary practices that God has ordained. This means a regular participation in the Lord's Supper. Indeed, "frequent communion" was too weak a term for J. Wesley; he urged us to "constant communion," that is, to receive it as often as we can ("The Duty of Constant Communion," Works 3  431).
The Lord's Supper conveys not only sanctifying grace, but justifying and even preventing (or prevenient) grace. Here Wesley puts himself at odds with much of the Christian tradition. Most of that tradition would say baptism (often linked to conversion or regeneration) was the necessary prerequisite for coming to the Lord's Table. Many Puritans would require in addition an intensive period of repentance as preparation to receive the sacrament. Yet Wesley makes neither an absolute requirement.
It is true that in Wesley's day there were relatively few unbaptized adults in England. But there were many who were baptized yet manifestly not Christian: they did not trust in Christ for their salvation, neither feared nor loved God, and did not love their neighbor. Many trusted in the fact they were baptized, which Wesley thought was a dangerous illusion if, instead of leading to new life, baptism becomes a substitute for faith in Christ.
Unlike the early centuries of the church, when baptism was the culmination of a process of Christian formation, in Wesley's day baptism was neither the culmination nor the beginning of such a process. Wesley's spiritual discipline and class meetings served as a functional equivalent to that formational process.
Wesley was convinced that, baptized or not, the Lord's Supper could both awaken persons to their sinful condition and serve as a converting ordinance. If persons come with any degree of faith at all, even that of a sincere seeker, they will meet Jesus Christ in this sacrament, and through that gracious encounter be transformed.
Thus Charles Wesley could write hymns that invite everyone to the table: "Come, sinners, to the gospel feast, let every soul be Jesus guest. Ye need not one be left behind, for God hath bid all humankind! Come and partake the gospel feast, be saved from sin, in Jesus rest; O taste the goodness of our God, and eat his flesh and drink his blood, See him set forth before your eyes; behold the bleeding sacrifice; his offered love make haste to embrace, and freely now be saved by grace" (The United Methodist Hymnal, #616).
Yet the Lord's Supper remains a primary means of sanctifying grace. Christians grow in the knowledge and love of God as they encounter God's love afresh in this sacrament. All who desire their hearts to be perfected in love should come ready to receive life from God. As C. Wesley said, in the Lord's Supper "we thirst for the Spirit that flows from above, and long to inherit thy fullness of love" (The United Methodist Hymnal, #635).
For the Wesleys this table is a gift for everyone, seeker and Christian alike. God meets all who accepts the invitation, and draws them closer to receive the fullness of life that God gives.