Right you are...but he gave man/doctors the knowledge to perform it for their religious or medical reasons.
The religious origin of the Jewish practice of circumcision is written in the Torah where God promised Abraham,
I will make you exceedingly fertile, and make nations of you, and kings shall come forth from you. . . . I assign the land you sojourn in to you and your offspring to come, all the land of Canaan, as an everlasting holding. I will be their God. . . . Such shall be the covenant between Me and you and your offspring to follow which you shall keep: every male among you shall be circumcised. (Genesis 17:6,8,10)