In his book Intro. to Christianity, he explains it very well. Being a Christian means to turn away (convert) from the material world. This conversion has to be an everyday event. Baptism represents the first conversion. The first time that when asked if you believe in God, Jesus Christ and the Holy Spirit, you respond I - do.
The Pope explains it much better than I ever could, and that book is perhaps the best I’ve read in a long, long, time.
But I still say that infant baptism is strictly a Roman Catholic practice (with its Anglican and other imitators). Christians believe in true repentence, which only a thinking person can accomplish. Some do at an age of six or so, but a baby isn’t capable of repentence. That means he can’t be born again at that time.