Article I, Section 8 of the Constitution authorizes the Congress to maintain an army and a navy. Beyond the regular armed forces, the militia was the principal means conceived to protect the homeland from foreign invasion or domestic insurrection. The aforementioned Section addresses this issue: "To provide for organizing, arming, and disciplining the Militia, and for governing such Part of them as may be employed in the Service of the United States, reserving to the States respectively, the appointment of the Officers, and the Authority of training the Militia according to the discipline prescribed by Congress."
The question arises as to who would constitute the militia. The Militia Act of 1792 stated that every able bodied, free male should keep a military firearm at their residence. The implication of the statement is that the militia, generally speaking, represents all able-bodied men in the community. Legal scholar Joyce Lee Malcolm, in a 1983 paper, "The Right of the People to Keep and Bear Arms: The Common Law Tradition," discusses the English common law origin of the militia. "During most of England's history, maintenance of an armed citizenry was neither merely permissive nor cosmetic but essential. Until late in the seventeenth century England had no standing army, and until the nineteenth century no regular police force. The maintenance of order was everyone's business and an armed and active citizenry was written into the system. All able-bodied men between the ages of sixteen and sixty were liable to be summoned to serve on the sheriff's posse to pursue malefactors or to suppress local disorders. For larger scale emergencies, such as invasion or insurrection, a civilian militia was intermittently mustered for military duty."
Clearly all men, within certain age brackets, were considered part of the militia. Fines and punishment were in order for those who refused to participate. However, the general training of the militia and the appointment of offiers were reserved to the states. Alexander Hamilton, in Federalist Paper No. 29, provides insight as to what the Founding Fathers intended. "To oblige the great body of the yeomanry, and of the other classes of the citizens, to be under arms for the purpose of going through military exercises and evolutions, as often as might be necessary to acquire the degree of perfection which would entitle them to the character of a well-regulated militia, would be a real grievance to the people, and a serious public inconvenience and loss. It would form an annual deduction from the productive labor of the country, to an amount which, calculating upon the present numbers of the people, would not fall far short of the whole expense of the civil establishments of all the States."
It would appear that Hamilton and the Framers of the Constitution did not intend for a mass army. Elsewhere in Federalist Paper No. 29, Hamilton notes that if the Framers intended to use the militia as a mass Federal army, the states would not have been given the exclusive power to appoint officers. In addition, the Tenth Amendment reserves those powers not specifically authorized to the Federal government to the states and the people.
The Federal government is not empowered to draft the citizenry for service in the armed forces by the Constitution. That document may not forbid compulsory military service imposed by the states as part of their repective militias.
With respect to Biblical arguments, Exodus 20:15 states: Thou shalt not steal. The question arises as to whether complusory military service is theft. Christian philosopher John Robbins offers these comments; "Two common misconceptions must be eliminated if we are to understand the meaning of this Commandment. First, the Commandment does not refer only to inanimate property. The Hebrew word is used in connection with both property and persons, and in Exodus 21:16 we read of 'manstealing,' i.e., kidnapping, which is a capital crime. This commandment clearly forbids not only the theft of property, but also the removal of innocent persons against their will. The second misconception is that the Ten Commandments, including this one, apply only to private individuals and not to governments. This notion, which has absolutely no foundation in Scripture, illustrates how far we have gone toward deifying government, for it is attributing divine qualities to rulers to say that they in their official (or private) capacities are exempt from the law. The Commandments, as both the Bible and the Westminster Confession say, bind all men without exception. Rulers and governments are commanded not to steal, murder, covet, lie, or do any other act prohibited in the moral law."
The fact that the Federal government, during the War between the States, the two World Wars, and the period from 1948 to 1973 (Korea and Vietnam), maintained a military draft does not make these actions in conformance with the original intent of the Framers of the Constitution, much less a moral act. It is one of but hundreds of activities in which the Federal government engages that clearly contravenes the principles of limited government and liberty upon which America was founded.
Conscription is a bad idea unless it is strictly necessary. But it's definitely not a contravention of the Constitution, nor is it an overreach of government. This is one of the few places where government is absolutely necessary -- to provide for the common defense. Even a libertarian would grant that.