My question is this. Without grace there is no justification, no salvation. Grace, then, is the paramount necessity for salvation. Grace is absolutely necessary for salvation.
Baptism is also necessary for salvation, because justification an grace are conferred in baptism.
The necessity of baptism for salvation is treated in nos. For baptism or any other sacrament to be given, there are certain objective standards which must be fulfilled in order for the sacrament to exist at all. In addition to these, it is necessary for the minister to have the intention of doing what the Church does. The Councils of Constance and Trent have the same teaching. Now, in the case of an infant, the baptism is certainly valid if the priest with proper intention performs the integral rite.