What, then, is the propagation of the faith? I suggest another question. What is the faith? Here a hundred isms rise up, and I put them all aside; they may be phases of the faith, but they are not the faith. What, then, is the faith?
Strange to say, the faith of Christians is a Person.
You may ask all other religions wherein their faith lieth, and they cannot answer on this wise. Our faith is a Person; the gospel that we have to preach is a Person, and go wherever we may, we have something solid and tangible to preach.
If you had asked the twelve apostles, in their day, "What do you believe in?" they would not have needed to go round about with a long reply, but they would have pointed to their Master, and they would have said, "We believe Him."
"But what are your doctrines?"
"There they stand incarnate."
"But what is your practice?"
"There stands our practice. He is our example."
"What, then, do you believe?"
Hear ye the glorious answer of the apostle Paul, "We preach Christ crucified."
Our creed, our body of divinity, our whole theology is summed up in the person of Christ Jesus.
The apostle preached doctrine, but the doctrine was Christ.
He preached practice, but the practice was all in Christ.
There is no summary of the faith of a Christian that can compass all he believes, except that word Christ;
and that is the Alpha and the Omega of our creed,
that is the first and the last rule of our practice - Christ, and Him crucified.
To spread the faith, then, is to spread the knowledge of Christ crucified. It is, in fact, to bring men, through the agency of God's Spirit, to feel their need of Christ, to seek Christ, to believe in Christ, to love Christ, and then to live for Christ.
Charles Spurgeon, Autobiography: Volume 2, The Full Harvest (Carlisle: Banner Of Truth, 2006), 122-123.