What is it that grows a church? Here's Spurgeon's answer:
Are you afraid that preaching the gospel will not win souls? Are you despondent as to success in God’s way? Is this why you pine for clever oratory? Is this why you must have music, and architecture, and flowers and millinery? After all, is it by might and power, and not by the Spirit of God? It is even so in the opinion of many.
Brethren beloved, there are many things which I might allow to other worshippers which I have denied myself in conducting the worship of this congregation. I have long worked out before your very eyes the experiment of the unaided attractiveness of the gospel of Jesus. Our service is severely plain. No man ever comes hither to gratify his eye with art, or his ear with music. I have set before you, these many years, nothing but Christ crucified, and the simplicity of the gospel; yet where will you find such a crowd as this gathered together this morning? Where will you find such a multitude as this meeting Sabbath after Sabbath, for five-and-thirty years? I have shown you nothing but the cross, the cross without flowers of oratory, the cross without diamonds of ecclesiastical rank, the cross without the buttress of boastful science. It is abundantly sufficient to attract men first to itself, and afterwards to eternal life!
In this house we have proved successfully, these many years, this great truth, that the gospel plainly preached will gain an audience, convert sinners, and build up and sustain a church. We beseech the people of God to mark that there is no need to try doubtful expedients and questionable methods. God will save by the gospel still: only let it be the gospel in its purity. This grand old sword will cleave a man’s chine [i.e., spine], and split a rock in halves.
How is it that it does so little of its old conquering work? I will tell you. Do you see the scabbard of artistic work, so wonderfully elaborated? Full many keep the sword in this scabbard, and therefore its edge never gets to its work. Pull off that scabbard. Fling that fine sheath to Hades, and then see how, in the Lord’s hands, that glorious two-handed sword will mow down fields of men as mowers level the grass with their scythes.
There is no need to go down to Egypt for help. To invite the devil to help Christ is shameful. Please God, we shall see prosperity yet, when the church of God is resolved never to seek it except in God’s own way.Charles Haddon Spurgeon
Metropolitan Tabernacle Pulpit, 1888, vol. 34, p. 563