Pestalozzi was brought up to be a very religious Protestant Christian. His grandfather was a pastor in the village of Höngg, near Zurich, and his school education would also have been religious. Pestalozzi considered becoming a pastor but later decided not to. However, he continued to be a religious person throughout his life and always believed that man was answerable to God. Throughout his life, Pestalozzi thought about the nature of religion and about the importance of a religious life. Pestalozzi's wife, Anna Schulthess, also came from a religious family and was educated to be very pious. Both of them would have wanted to marry only someone who shared the same basic religious beliefs.

Pestalozzi's theological convictions were influenced by the religious education he had received, meaning that they were determined by Pietism. The Pietists rejected rationalist discussions about the texts of the Bible and held themselves distant from culture and the fine arts. They thought that religion was a matter of the heart and not of the head. They strove for simplicity in their worship and for a life without luxury, in which they worked for the service of fellow humans. Affiliation to a particular Christian church was unimportant to them; to them it was essential to live in small communities and have love for each other.

Rousseau was the other main influence on Pestalozzi’s religious beliefs. Rousseau was not an atheist, as many comrades-in-arms of the European Enlightenment were. However, Rousseau did not base his faith on the Bible. He questioned the authority of the church. His religious beliefs were rooted in his own emotional convictions and in his own rational thinking.

Pestalozzi came across Rousseau's way of thinking in the latter’s famous educational novel 'Emil'. In it, Rousseau explains his basic philosophical and theological ideas, the summary of which is as follows: 

There is an intelligent will. This will moves the universe and gives life to nature. Rousseau calls this intelligent will ‘God’. With this ‘intelligent will’ or ‘God’ he connects intelligence, power, will and kindness. He knows that God exists and believes that his own existence is subordinate to God’s. Therefore he worships and serves God. He perceives God in all his works and feels Him inside himself. In human nature he recognises two clearly distinct principles. One elevates humans so that they search for the eternal truths - love, justice and morality - and so that they are lifted into the regions of the spirit. The other drags humans down into themselves, to be ruled by the senses and the passions. Humans are free in their actions. They are free beings animated by an immaterial substance which survives physical death. Evil does not come from God, but from humans. God does not want evil, but does not stop humans from committing evil, because he does not want to restrict their freedom. God created humans as free beings, so that they could choose to not commit evil and to do good. The conscience of humans knows what justice and virtue are and always tells them what is good.  As for the Bible, it speaks to Rousseau’s heart, but he does not accept it as binding revelation.

Pestalozzi links Rousseau’s ideas with Pietism. Both Rousseau and the Pietists give the heart priority over the intellect and emphasise the importance of simplicity of faith. These ideas are found in Pestalozzi's theological convictions throughout his life. He is often actually hostile towards theology. Pestalozzi believed that people should feel God in their hearts, not by using their intellect or basing their beliefs only on what they are told by religious authorities.

Pestalozzi also shares with Rousseau the simple emotional certainty that after death humans live on in an immaterial world and that this existence after death depends on their conduct in life in this world. This idea is also part of orthodox Christian thinking, but orthodox Christians believe this because the Bible says this, whereas Pestalozzi – just like Rousseau – bases his belief on his own thinking and feelings. Also like Rousseau, Pestalozzi refused to think any further on life after death, and did not wish to form concrete ideas on this topic.

In contrast to some Christian theologians – and in agreement with Rousseau – Pestalozzi also felt that he did not have the right to say too much about the nature of God, so he only said that he felt that goodness, justice and love are all godly qualities. He believed in the idea of God as Father and thus saw himself as a child of God. He therefore reciprocated God’s love with love for God, with trust in God and with gratitude towards God.

Pestalozzi understands God as a being who lives outside people’s hearts as well as a being who acts inside people’s hearts. He speaks of the ‘Father in Heaven’ or of man as the ‘Child of God’ and he also speaks of ‘God at the core of my nature’.

Like Rousseau and like traditional Christians, Pestalozzi is convinced that the belief in God felt really deeply in a human being’s heart is what stops him from seeking the pleasures of life at the expense of fellow human beings and is the main reason for people wanting to overcome their own egoism. Therefore Pestalozzi’s moral education is closely connected with religious education; indeed he often speaks of ‘moral-religious education’ as an inseparable unit.

Pestalozzi believed that religiousness should be evident in people’s day-to-day actions and should bring about moral behaviour and acts of love. He did not believe in a religious practice which paralysed a person’s interest in worldly affairs and which alienated him from the world.

Many of Pestalozzi’s statements about religious issues have made people wonder if he can be called a Christian, in the normal sense in which this word is used. Throughout his life Pestalozzi tried to live according to the teachings of Jesus but his theological opinions show that he refused to be pinned down to certain central dogmas of Christian theology. Pestalozzi’s religious beliefs were certainly closer to Rousseau's natural religion than to traditional Protestantism.

One way in which Pestalozzi was not an orthodox Christian was that he never thought that the bible contained the ultimate revelation on which a person’s faith should be based. This did not stop him from reading the Bible very closely and from allowing himself to be enriched by it. He did not feel the need to evaluate the Bible theologically or to draw conclusions from it, but he tried to live his life and take action based on his heart’s understanding of the bible. He would never have relied on only the Bible in making a decision to act, but reading the Bible was his incentive to seek truth and to realise love.

Pestalozzi believed that human life must be understood from three different points of view; as a natural, a social or a moral process. This perception, indeed, makes it possible for Pestalozzi to differentiate religion and to show its anthropological importance.

According to Pestalozzi, in the ‘unspoilt natural state’ humans do not have any religion, because animal innocence does not sacrifice or bless or curse. In the spoilt natural state religion is superstition; humans pray to the inexplicable aspects of nature and call them God. Humans imagine a God who has human characteristics.

In the social state, religion is a source of advice and help and leads to the invention of various arts, but according to the needs and advantages of a state it soon becomes egotistical, hostile and vindictive. The religion of humans in the social state of being can easily become the servant of the State and therefore a deception. God, according to the social person, fights for those who worship and adore Him and rewards them for this worship and adoration.

Only in the moral state is true religion possible for a human being, when it helps him to strive for being the noblest that he can be. Just like morality, religion is absolutely individual, a perception of the divine reality in the innermost core of the heart. It is does not exist in words but in actions of love.

Pestalozzi characterises the religiousness of a person in the natural and in the social state as merely ritual. All outer ceremonies, religious customs and rites, and also everything ecclesiastical and canonical are part of such religiousness. In contrast to these rituals, the religiousness of man in the moral state is divine.

It is typical of Pestalozzi that these thoughts do not make him object to the ritual religion of the natural or of the social man. He recognises that both forms of ritual religion are essential as ways of conveying God to humans through the senses. However the rituals of religion – i.e. everything externally visible, everything graphic, everything ecclesiastical or social – should not prevent the divine, since the means would then defeat the end.

Pestalozzi believes that the best religion is the one which is the most divine in its inner nature, while being the least possibly ritualistic in its form. He does also say that it needs to be sufficiently ritualistic to ensure that it is a sufficient help to man in his struggle against the animal side of his nature. In Pestalozzi's opinion Christianity best fulfils these conditions, for he is convinced that Christianity is totally moral and that it is therefore also entirely an affair of the individual.

The conviction that Christianity was the best religion did not stop Pestalozzi from showing religious tolerance in living together with his fellow humans. He is never known to have tried to change another person’s religious opinions. The only people he could not tolerate were hypocrites who pretended to be pious in order to exploit or suppress their fellow men. Then he spoke out and showed what he believed to be the truth.

Pestalozzi saw himself as a Christian but certain theologians were of a different opinion. So it is important to illustrate how Pestalozzi thought about the most basic Christian dogmas.

Traditionally Christians believe that Jesus is God, that humans are all guilty of ‘original sin’ (original sin is the Christian belief that every human is born with a tendency to evil, inherited from Adam in consequence of the Fall), that humans can be redeemed by faith in God, and that Jesus is the saviour of humankind because he washed away collective human sin by his sacrifice – his death on the cross.

Pestalozzi’s beliefs differ from the beliefs of traditional Christians. He avoids making a definite statement as to whether Jesus is God or not. All of his writings prove that he considered Jesus the divinely perfect man, in whom the divinity generally possible in a human has come to perfection. Jesus was Pestalozzi’s model and redeemer through his example and his teachings.

Pestalozzi did not consider people to be guilty of 'original sin'. He only believed that humans are shackled to their sensuality and egoism.

Pestalozzi did not share one of the most important dogmas of the reformers – that faith is enough to redeem a person. He did not agree that simply by believing in God people could be redeemed in any sense.  

Pestalozzi did not believe that humankind’s collective sin was washed away by Jesus’ sacrifice of himself on the cross. Rather, he sees Jesus as saviour because he believes that humankind could be free of all unkindness and ensnarement by living like Christ did. With so much misery and suffering in the world, Pestalozzi believed that everyone could live as a saviour.

In the end, the question, ‘Is Pestalozzi a Christian?’ has a different answer according to the different definitions of ‘Christianity’ that different people have.