The dangers of being a credobaptist
It's no secret that I've not always been Reformed. I was actually raised in a Baptist church and slowly became reformed, but that is a whole story itself. Needless to say though the last major obstacle I had to joining the RCUS was infant baptism. I could readily see Calvinism in the scriptures, but for a long time I didn't understand why they insisted on baptizing their babies. It wasn't until I understood the covenant of grace that this made sense--had to get rid of that whole thinking that the Old Testament is totally irrelevant today.
Either way, I don't wish to make a full argument for paedobaptism right now--let's leave that to those more experienced. I want to suggest there are some dangers about being a credobaptist and not baptizing your children. My basis for this is found in Genesis when circumcision was instituted:
You shall be circumcised in the flesh of your foreskins, and it shall be a sign of the covenant between me and you. He who is eight days old among you shall be circumcised. Every male throughout your generations, whether born in your house or bought with your money from any foreigner who is not of your offspring, both he who is born in your house and he who is bought with your money, shall surely be circumcised. So shall my covenant be in your flesh an everlasting covenant. Any uncircumcised male who is not circumcised in the flesh of his foreskin shall be cut off from his people; he has broken my covenant."
(Gen 17:11-14 ESV)
Baptism and circumcision both point to the same reality--the washing away or the cutting away of sin (see Colossians 2:11-12). Both also signify the entrance into the visible church in their respective testaments. This being said, it is a very scary thought when you read this passage. God is saying that those who reject the sign of the covenant are rejecting what the sign points to. The true Jew knew that circumcision does not save a person; just as the true Christian today knows that baptism does not save a person. And yet, a rejection of the sign was a rejection of the covenant itself.
Now, as Peter said at Pentecost, the New Testament promise is to us, our children, and all who are afar off. Note that the change in the formula is not a removal of our children from the promise, but an addition of the Gentiles. This would indicate that the children of Christian parents are still heirs of the promise just as the Jewish children were in Israel's time. It would not make any sense for Peter to be saying that the promise (i.e. the covenant) was still unto the children of believers and yet not have the sign of the covenant applied to them.
Here's where the danger comes in; if it was considered a rejection of the covenant by those who refused circumcision to their children in the Old Testament, how much more dangerous is it for those who refuse to baptize their children in the New Testament when the revelation is so much clearer. After all, the author of Hebrews councils us to pay closer attention to the things of the New Covenant because if the things spoken by angels (the Old Covenant) proved steadfast, then how much more attention should we pay to the things spoken by the Son of God Himself? This would seem to make it an extremely foolish act to not baptize covenant children--if you are a believer. God does not take the rejection of his sign lightly.