In the following decades, various attempts were made to breach the wall of separation and gain some official recognition and status for Christianity. Isaac Kramnick and Laurence Moore, in their excellent book, The Godless Constitution: The Case against Religious Correctness (W.W. Norton, 1997), describe two such efforts in considerable detail.
Sunday Mail. In 1829, after religious leaders had attempted to force the mail service to stop all activity, including the moving of mail, on Sundays, the Senate issued a formal report stating that Congress is "a civil institution, wholly destitute of religious authority" and that Legislators have no power to "define God or point out to the citizen one religious duty” or "to coerce the religious homage of anything," including the Sabbath. "The line cannot be too strongly drawn between church and state," the report said, and prohbiting Sunday mail is "legislating upon a religious subject and therefore unconstitutional."
A Christian Amendment. As they had since the ratification debates, many Christians continued to lament the dissociation between religion and government, particularly in times of crisis. During perhaps the greatest of all national crises, the Civil War, a group of prominent churchmen calling themselves the National Reform Association began pushing for a Constitutional amendment that would amount to rewriting the preamble “acknowledging Almighty God as the source of all authority and power in civil government, The Lord Jesus Christ as the Governor among the Nations, and His revealed will as of supreme authority, in order to constitute a Christian government....etc.” A delegation of prominent members of the association visited President Lincoln in 1864 and asked him to support it in Congress. Lincoln said he needed to study the matter further, but never got around to it. Congress ignored the proposed amendment in 1864 and again in 1869. Major, but losing, efforts to insert Christ into the Constitution were made in 1894 and 1910; in 1947 and 1954, the National Association of Evangelicals campaigned for such a measure. All such efforts have failed, so far.
As Kramnick and Moore point out, it is a gross distortion of history to contend that the Constitution was designed to produce a Christian nation and that secularists have worked to erode that sacred character. The pressure has come from the other direction.