The Doctrine of Baptism

http://www.churchsociety.org/issues_new/doctrine/heads/iss_doctrine_heads_baptism.asp

[Church Society] May 13, 2006--In Anglican teaching baptism without repentance and faith is an empty sacrament devoid of grace. Repentence and faith may precede baptism or follow it but without it baptism has no effect.

Does baptism do anything?
In Anglican teaching the two sacraments (Baptism and the Lord's Supper) are more than just signs or symbols. Rather they are sure witnesses and effectual signs of God's grace and good will towards us. Through them he works invisibly within us, both bringing to life and also strengthening and confirming our faith in him. (Article 25).

Does it always do something?
However Anglicans do not teach an ex-opera ex-operato view of the Sacraments as the Church of Rome does. This latter view is that sacraments have power in an of themselves. Rather the sacraments are only effective in those that receive them worthily.

What is necessary for baptism to be effective?
Article 25 teaches that baptism must be received worthily. The Articles do not expand on this. However, the baptism service does in that the congregation are exhorted to pray that God will receive theise 'these present persons, truly repenting, and coming unto him by faith'.
The condition for baptism to be effective is that it is accompanied by repentance and faith.