In Matthew 13, Jesus tells a parable about the Kingdom of heaven using a tiny seed.

“The kingdom of heaven is like a mustard seed, which a man took and planted in his field. Though it is the smallest of all seeds, yet when it grows, it is the largest of garden plants and becomes a tree, so that the birds come and perch in its branches.”

The message is clear. God works in small ways to bring about big changes. I think of it this way: even a little grace makes a big difference.

That metaphor has inspired me to plant seeds of grace with these small posts that I pray will make a big difference in your life as they germinate in your heart, mind, and soul, helping you come alive to the wonder, beauty, and liberating power of the gospel — the “good news” message from God that centers on the life, death, and resurrection of the reigning Jesus.

If you find any article particularly helpful, I’d love to hear how your life is being impacted. Feel free to share in the comment section or email me directly at mckaycaston@gmail.com.

Yours, by grace alone,

McKay


See below👇🏼 for details about The Mustard Seed content philosophy and how it ties together three core doctrines: justification, adoption, and sanctification.


Dr. Tim Keller says, “The key to spiritual renewal is the continual re-discovery of the gospel.”

Keeping with that philosophy, the message of the cross looms large in every post, with the goal being a “continual re-discovery of the gospel." Tethering all of my content to the cross, I long for believers to have eyes to see, celebrate, and savor the present value of Jesus’ blood.

If there is a word that most encapsulates the theological foundation of the gospel, it is substitution.

This is why every piece of content you will find here touches on the concept of “Jesus in my place.” He lived in the sinner’s place, achieving an actual record of perfect righteousness with which to replace the rags of unrighteousness and self-righteousness. He also died in the sinner’s place, satisfying in full the demands of justice our sin deserved. As sin-bearer and righteousness provider, Jesus is the sinner’s substitute in life and death, with his resurrection serving to confirm these extraordinary gospel promises are true.

When someone consciously believes the gospel, the Spirit engrafts them into Jesus like a branch is connected to a vine. Theologically, we call this union with Christ, where the believer abides in him by faith, believing that Jesus’ perfect righteousness is now his or her perfect righteousness (their new and true identity). As they press into the vine with a present awareness of the value of Jesus’ blood, the Holy Spirit, like sap from the vine, flows into and fills the disciple with new desires and abilities, changing him or her from the inside out. This change does not take place by trying harder, making promises, or resolving to be more religious, but by consciously abiding by faith in the gift-righteousness of Jesus as one’s Justifier and my Sanctifier.

"As a believer presses into the vine with a present awareness of the value of Jesus’ blood, the Holy Spirit, like sap from the vine, flows into and fills the disciple with new desires and abilities, changing them from the inside out."

And we haven’t even touched on the most powerful gospel reality—spiritual adoption. If justification is the legal foundation of grace, adoption is the relational, experiential atmosphere of grace. No longer do I relate to God as a disappointed, angry judge. He is a loving, compassionate, kind, strong, "for us" Abba, Father.

This is why a cross-centered theology of union through substitution that leads to personal transformation is the foundation for The Mustard Seed.


Three Core Doctrines

#1 — JUSTIFICATION: Grace-Centered Theology

At the heart of all of Scripture is the redemptive message of God’s saving grace to sinners in Jesus. Theologically, we call this justification, which is the hub of the theological wheel to which every passage and doctrine is connected. This grace message is the oak from which every acorn of biblical text falls and must be related in order to be properly understood and applied.

"The doctrine of justification by faith through the substitutionary sacrifice of Christ is very much to my ministry what bread and salt are to the table. As often as ever the table is set, there are those necessary things. I regard that doctrine as being one that is to be preached continually, to be mixed up with all of our sermons.” — Charles H. Spurgeon, Sermon #3488, October 9, 1870


#2 — ADOPTION: Grace-Focused Identity

Every human either will find his or her core identity in a self-achieved righteousness or in a gift-received righteousness. We will functionally live as spiritual orphans trying to make a life and name for ourselves, or we will live like adopted and beloved sons and daughters, with all the freedom, peace, hope, and joy that flows from such an identity. The implications are manifold and wide-ranging, touching on practically every area of life. 

“Adoption is the highest privilege of the gospel. The traitor is forgiven, brought in for supper, and given the family name. To be right with God the Judge is a great thing, but to be loved and cared for by God the Father is greater.” — J.I. Packer


#3 — SANCTIFICATION: Grace-Empowered Transformation

What now? Should I expect to experience a spiritual change in my life? If so, how does that take place? What is my role in the process?  As Jesus says in John 15, “No one can produce good fruit apart from me.” Practically speaking, this means that we experience the fruit of the Spirit as we consciously abide in the Vine of Jesus’ imputed gift-righteousness. As the Spirit fills us like sap through a vine into a branch, we receive new motives and a new ability to manifest the new life of love, peace, patience, kindness, etc.

“It is by simple, close, and searching views of the cross of Christ that the Spirit most effectually sanctifies the believer. This is the true and great method of gospel sanctification! Let no man dream of true mortification of sin, or real sanctification of heart, who does not deal constantly, closely and believingly with the atoning blood of Jesus.” — Octavius Winslow, The Work of the Holy Spirit (129)