From the SDA Spirit of Prophecy writings: (this pretty well sums it up)
Baptism Requisite in Conversion.--Repentance, faith, and baptism are the requisite steps in conversion. Letter 174, 1909. {Ev 306.3}
The Christian's Oath of Allegiance.--As Christians submit to the solemn rite of baptism, He registers the vow that they make to be true to Him. This vow is their oath of allegiance. They are baptized in the name of the Father and the Son and the Holy Spirit. Thus they are united with the three great powers of heaven. They pledge themselves to renounce the world and to observe the laws of the kingdom of God. Henceforth they are to walk in newness of life. No longer are they to follow the traditions of men. No longer are they to follow dishonest methods. They are to obey the statutes of the kingdom of heaven. They are to seek God's honor. If they will be true to their vow, they will be furnished with grace and power that will enable them to fulfill all righteousness. "As many as received Him, to them gave He power to become the sons of God, even to them that believe on His name.--Letter 129, 1903. {Ev 307.3}
A Worthless Form Apart From Christ.--It is the grace of Christ that gives life to the soul. Apart from Christ, baptism, like any other service, is a worthless form. "He that believeth not the Son shall not see life."--The Desire of Ages, p. 181. (1898) {Ev 318.3}
Conversion, Not Just Baptism.--Salvation is not to be baptized, not to have our names upon the church books, not to preach the truth. But it is a living union with Jesus Christ to be renewed in heart, doing the works of Christ in faith and labor of love, in patience, meekness, and hope. Every soul united to Christ will be a living missionary to all around him. --Letter 55, 1886. {Ev 319.1}