Alvin Plantinga capsizes the idea of classical foundationalism in his work called Religious Belief Without Evidence. Foundationalism is the idea that beliefs are justified only if they are founded upon what is referred to as basic beliefs. Basic beliefs are those that are grounded within something other than other beliefs. Classical foundationalism is a version or form of foundationalism in which it offers certain criterion for what counts as a basic belief. Plantinga notes classical foundationalism says “some propositions are properly basic and some are not; those that are not are rationally accepted only in the basis of evidence, where the evidence must track back, ultimately, to what is basic.” The criteria to ascertain if a belief is basic or not under classical foundationalism is as follows: something that is self-evident (something that is intuitive to all thinking individuals), something that is incorrigible (something that cannot be corrected), and evident in the senses (something that is based obvious from the senses). If these judgments of criteria are true, this creates problems for theistic belief. Theistic belief can be described as not self-evident to all people. Some could argue that belief in the existence of a deity is corrigible. Furthermore, obviously an existence of God cannot be found from sense perception.
Plantinga responds to the objection to God’s existence by demonstrating the fallaciousness of the criteria for classical foundationalism. The philosopher argues, if classical foundationalism is true, then enormous quantities of what we all as people believe is irrational. Many propositions that do not meet the criteria of classical foundationalism are properly basic for many people. Furthermore, classical foundationalism does not even meet its own criterion. It is self-defeating. It is not self-evident, incorrigible, and evident in the senses to believe in the criterion given for the system. There are certain things people believe that do not meet the criterion offered under the system of classical foundationalism (e.g. How do you know you’re not in the matrix? How do you know that other minds exist? How do you know the world was not created five minutes ago with some fixed memory built in?).
Plantinga thinks we are justified in our belief in the existence of God because it is a properly basic belief. By examining what John Calvin, Karl Barth, and Herman Bavinick said concerning natural theology, Plantinga concludes that belief in the existence of God is not determined by the arguments, but is built in from the source of the Creator himself into creatures. Following the proponents of sensus divinitatis, God has created all human beings with an innate ability that inclines them in appropriate circumstances to believe in God. Calvin himself said:
There exists in the human minds and indeed by natural instinct, some sense of Deity, we hold to be beyond dispute, since God himself, to prevent any man from pretending ignorance, has endued all men with some idea of his Godhead, the memory of which he constantly renews and occasionally enlarges, that all to a man being aware that there is a God, and that he is their Maker, may be condemned by their own conscience when they neither worship him nor consecrate their lives to his service.
Plantinga can conclude that we can believe in God without any evidence based upon this line of thinking. I tend to agree with Plantinga based upon my own experience within this world and knowing the experiences of others around me. There are inherent religious tendencies in most people and cultures around the world. Even Scripture speaks of some things being generically revealed about God from either the world we live in or within our own consciences (Psa. 19; Rom. 1:18-23; 2:14-16, Acts 14:15-17). Though holding that belief in God is a properly basic belief, Plantinga articulates many theistic arguments within his works (here).