marge good friend
Maybe its hard to prove, to the unbeliever, but it is scriptural.
Remember faith is a sign of righteousness(faith is one of the virtues) to Abraham before he was circumcised, and then became circumcised....Romans 4:11
The effects and effectiveness are by God's Grace and man's acceptance of that Grace.
Baptism is a seal as is circumcision....
Water baptism & circumcision are not seals as I understand Scripture. These are mans public declarations. A distinction is made however in the following Scriptures;
However, a Holy seal, is given from Holy God and only by Holy God can they be given.
11I indeed baptize you with water unto repentance: but he that cometh after me is mightier than I, whose shoes I am not worthy to bear: he shall baptize you with the Holy Ghost, and with fire.
In whom ye also trusted, after that ye heard the word of truth, the gospel of your salvation: in whom also after that ye believed, ye were sealed with that holy Spirit of promise, 14Which is the earnest of our inheritance until the redemption of the purchased possession, unto the praise of his glory.