Mikveh Israel was created in 1870.

Baptism is very much needed to show you have become a changed person , and believe in christ, However it is not a Jewish ritual. It is based on the Jewish ritual of the Mikveh (מקוה), but the Mikveh is quite different.

For example, If you are born into the Jewish religion, you do not need to do the Mikveh ritual. Also, The Mikveh is more than just a conversion rite. It is a used after an illness, before weddings, and after menstuation, among other things.

Ask an Orthodox rabbi.

The word mikveh in Hebrew literally means a collection. The word has come to refer to a ritual bath in which water is collected. The plural is mikvaot. A mikveh must be big enough for a person to wade into and then dunk, fully immersing his or herself. Mikvaot are used by women after their periods, by men for ritual purification, and as part of the ritual for conversion to Judaism.

There is no such thing as Jewish initiation. The mikveh is not used in a Bar Mitzva ceremony, which is the closest thing to the concept of "initiation" that I could think of. Nor is it part of a Brit (circumcision ceremony).

If a non-Jew converts to Judaism, immersion in a mikveh is the final stage of the conversion. Here too, the word "initiation" has synonyms that are more apt.