McNamara has accused Cardinal Sean Brady of misrepresenting the position with which the Oireachtas is required to legislate to give effect to the X-case.
In his Christmas message, Cardinal Brady said it is the Church's position that both mothers and unborn babies have an equal right to life.
He urged people who believe the right to life is fundamental, to make their voice heard in a reasonable but forthright way to their public representatives.
In response, he said it is not a question of setting one life above the other.