“Love ger for your were gerim in the land of Egypt.” A Ger is not, strictly speaking, a convert who is a Jew forever. A Ger accepts Jewish sovereignty, including religious legislation. He cannot worship foreign deities, or even God, out of the Temple. He accepts the law of the land, including the religious law. He can be considered practically Jewish.

Likewise, Jews adhered to Egyptian religious practices while there. Recall that God tells Moses, “You fathers didn’t know me under this name.” They worshiped differently. It seems that they were uncircumcised because Joshua had to circumcise them before entering Canaan, and Moses’ son was originally uncircumcised. In Egypt, circumcision was reserved for priests. No doubt, Jews could not bring animal sacrifices because those animals were the Egyptian deities. Therefore the significance of Pesach sacrifice: we killed an Egyptian deity, and just couldn’t stay there.

Deut14:21: sell unclean carrion to ger. He accepts the major tenets of Judaism but not always the purity commandments. The definition was fluid: he had to purify himself in order to partake of Pesach sacrifice. There were different levels of observance among gerim, all the way to proselyte rabbis. Children of gerim were Jewish. An example for the current mass assimilation of non-Jews in Israel.
The perceived need for stringent conversions stems from an error in metaphysics: rabbis think that they miraculously transform a Gentile into a Jew. That is not the case. Tanakh describes many instances of foreigners joining the Jewish people. Not in a single such case are they called Jewish. A Gentile can only become a ger, a more or less stringent adherent to Judaism and/or a fellow of the Jewish people (like Heber). His child might be born with the Jewish soul, and surely his fourth-generation descendants are Jewish. The Torah teaches that an apostate’s descendants bear his guilt for him until the fourth generation—the maximum descent after which the descendant could still know the transgressor. By that analogy, the fourth generation after ger, if all of them lead Jewish lives, is fully removed from the practices of other nations.