My family and I toured a small church in Marseilles, France a few months ago. The baptistry was off on the side of the nave. As our tour group went into the baptistry to look around, I started noticing the symbolism.
In particular, the ceiling of the baptistry and the font (which was part of the stone floor) were eight-sided. As I was pointing this out to my family, a woman in our group asked me why these were eight-sided.
I explained that historically, most Christian baptismal fonts had eight sides to symbolize Christ’s resurrection and the in-breaking of the new creation; it also symbolizes the original creation in Genesis.
The point being that God created the world in six days, rested on the seventh, then the eighth day was the first day of the new creation.
Similarly, Jesus’ Passion Week began with his entry into Jerusalem on the first day of the week (Sunday), his work all week in Jerusalem which culminated with his crucifixion on the sixth day of the week (Friday – “It is finished” as Jesus said from the cross), and his rest in the tomb on the seventh day (Saturday). Finally, on Sunday (the first day of the week) he rose from the dead, which began the ushering in of the new creation (that is, his restoration of his fallen creation which was effected by his death and resurrection and which will be completed at his return).
Baptismal fonts therefore have eight sides, because Christian baptism connects the baptized with Christ’s death and resurrection and therefore re-births him/her into Christ’s image. The baptized is therefore part of this new creation, and will live with Christ and his people eternally after the resurrection. Baptism is therefore a promise made by God to the baptized that God has adopted the baptized as His child and will bring him/her into eternal life. These promises are made here and completed at Christ’s return.
Many present-day churches (like mine) still have eight-sided fonts for this reason, as did the older and ancient churches.
The pictures below are of the ceiling of the baptistry of the church in Marseilles, the font which was built into the floor, and the outside of the church.