If I say that my potion cures terrible diseases or that the Virgin Mary is appearing down my garden the burden of proof is on me. I am the one that has to prove it. If I don't or if I can't, I am demeaning the people to whom I am voicing my claims. It is not up to them to prove me wrong though they can at least try if they wish.

In science as in law, the burden of proof is on the one making the claim. The more outrageous the claim the stronger the proof that is required.
If there is a number of theories about anything, I must adopt the theory that has the fewest assumptions. This theory might still be incorrect but that is not the point . The theory that is based on the fewest assumptions or guesses is the most likely one to be correct. We need it for practical reasons and for our benefit.

It is my business to supply my beliefs to others even if they are wrong beliefs as long as I am open to being shown to be wrong. If it is my business what I believe then it is my business if I believe I must make those beliefs available to others so that they might adopt them too.

If a religion does wrong we must state loudly what we believe and what we know. We must loudly declare the ways of righteousness. There is no need to criticise them. There is no need to condemn them. Such criticism is always a sign of spite. The answer is not criticism but discussion.
If people have a right to have religious beliefs then they have to admit that we have the right to ask them to be consistent. For example, if a religion claims to be the truth and it forbids people to think it is not respecting its own claim to be the truth. In fact it is disrespecting itself far more than any critic could ever disrespect it.

It is better to live the right way with joy than to preach to anyone. If you say encouraging things you will not need to preach. It is actions not words that speak to the hearts and draw them to the fountain of grace and mercy.

An example is when somebody fears loved ones going to Hell forever. If you say nothing you are putting religion before that person and encouraging and prolonging their pain. You should ask them, "Don't you think human nature is a mixture of bad and good? Would anybody really be bad enough to reject love forever?" You are not preaching to them. But you are helping them to get the courage to question things for themselves. That will work far better than preaching.

Religious faith and being made to conform to it can leave psychological scars. To eradicate such danger, material refuting religion must be made available to those who need it. But openly attacking a religion is unacceptable. If we show how wonderful the truth is by our way of life then we won’t need to condemn the faith of others and those who embrace it.

It can sound like one is criticising somebody's religion when one is not. For example, it is criticism to say that belief in a superior God is rubbish. But if you help people that belief in a superior God blocks self-esteem and is damaging that is not criticism but therapy. Its goal is to make you honour yourself in the place of God. To do that is to automatically honour others too. Such things need to be said for you have the right to encourage others to work for a happier world for you have to live in this world.

The Christian who tells the kindly and happy Muslim lady that Islam is wrong is criticising religion and demeaning her. The therapist who gently tries to help her see the truth about ideas that are upsetting and hurting her more than she realises is helping her.

When somebody makes outrageous claims to you, politely tell them that you need the proof.  You will meet many people who preach apparitions to you such as Knock but offer no evidence or even any sign that evidence means anything to them.

The Church says that apparitions of Mary have happened since Biblical times. However, you can disbelieve in them and still be a good Catholic. They are not part of the Catholic faith. The Church merely gives permission to believe in an apparition not a command. If an apparition contradicts Catholic doctrine, the Church forbids belief in the apparition by way of command.  It may give a direct command but if there is no direct command it is still covered by the law that out of respect say for Jesus and Mary you cannot be following appearances that are not from them.  Part of the condemnation of Spiritualism/spiritism in the Bible is about how having a relationship with a spirit you think is your deceased loved one and getting messages cheats you and insults them if it is not real.

Even the visionary is not bound to believe in their apparition. The Church says apparitions are only permitted to be believed in if they teach correct doctrine and if they don’t command anything strange or dangerous.

The Lourdes apparitions of 1858 are dubious for the story goes that Mary gave St Bernadette a secret to be kept for herself. She never told the Church investigators what it was. Thus the Church permission to decree the acceptability of belief in the apparition was invalid for they did not have all the information.

Mary supposedly appeared at a dirty disease ridden dump and had Bernadette eating plants there and thus risking her health. A spring appeared and Mary urged Bernadette to tell the crowd to use it. Bernadette tried to drink the water and stuffed soggy earth into her mouth. An apparition that nobody is bound to believe in has no right to command such harmful things. If you start saying, “Our Lady protected them from any harm”, you are really saying that people should take terrible risks for themselves and others on no other basis but faith.

The Knock apparition where Mary, St Joseph and St John seem to have appeared in 1879 with the Lamb of God on an altar seems very convincing on the face of it. But the Church did it's best to present the world with an altered version of what really happened.

Then there is Medjugorje where Mary has been appearing since 1981. Pilgrims go there and stare into the sun. Why no warning from Mary at Medjugorje not to look into sun? Does she not care about the huge number of cases of eye damage?

Medjugorje also presents her as having her messages distributed without being checked by Church authority. As the bishops for example know religion better than ordinary Catholics, Mary would at least honour that. Also, it is Catholic teaching that Jesus left his teaching authority with the bishops and the pope. Thus he cannot send an apparition that will contradict or undermine the authority of the bishop.

The messages being promoted by her are in disobedience to the Vatican.

The Vatican, The Congregation for the Doctrine of the Faith, November 1996

Regarding the circulation of texts of alleged private revelations, the Congregation states:

The Interpretation given by some individuals to a Decision approved by Paul VI on 14 October 1966 and promulgated on 15 November of that year, in virtue of which writings and messages resulting from alleged revelations could be freely circulated in the Church, is absolutely groundless. This decision actually referred to the "abolition of the Index of Forbidden Books" and determined that --- after the relevant censures were lifted --- the moral obligation still remained of not circulating or reading those writings which endanger faith and morals.

In should be recalled however that with regard to the circulation of texts of alleged private revelations, canon 623 #1 of the current Code remains in force: "the Pastors of the Church have the … right to demand that writings to be published by the Christian faithful which touch upon faith or morals be submitted to their judgment".

Alleged supernatural revelations and writings concerning them are submitted in first instance to the judgment of the diocesan Bishop, and, in particular cases, to the judgment of the Episcopal Conference and the Congregation for the Doctrine of the Faith.

Any apparition that breaks this rule, and the Medjugorje Virgin commands that her messages be distributed as they are received, is not a Catholic apparition or concerned about Catholic orthodoxy. The bishops are the official Catholic teachers not apparitions. The vast majority of modern visions break the rule and so are themselves disobedient apparitions.

The Catholic Church says that if you don't believe in miracles then you are saying that the wonderful testimonies from the most reliable of people that they happen are to be dismissed. The Church says that if people are that lacking in credibility, we can believe nothing they say. You can reply that you are not saying they must be dismissed or ignored. Trust means that you expect to hear sane things and decent things from decent people.