WASHINGTON — Tucked away in the Republican tax plan are several provisions that have little to do with overhauling the tax code and more to do with ensuring conservative lawmakers vote for the legislation.

The 400-plus-page bill released Thursday includes changes that would codify the rights of “unborn children,” allow tax-exempt religious organizations to engage in political activities and impose hurdles for immigrants seeking to claim refundable tax credits.

President Trump has long sought to appeal to religious and social conservatives, many of whom were initially wary of the candidacy of a thrice-married Manhattan billionaire who had openly boasted of his sexual conquests and displayed little interest in church or the Christian faith.

At a Values Voter Summit meeting here last month, Mr. Trump said he was committed to “stopping cold the attacks on Judeo-Christian values” and said the country’s religious heritage would be “cherished, protected and defended like you have never seen before.”