You don"t need sufficient amount of evidence to hold a belief. There is no way to determine what a sufficient amount of evidence even is. If we were to look at the beliefs all around the world, you will see how similar but different each belief is. You will see that the difference in our beliefs is what shapes our culture, our identity, and gives us a sense of individuality. "Are we then to become universal skeptics, doubting everything, afraid always to put one food before the other until we have personally tested the firmness of the road?" " William K. Clifford "The Ethics of Belief". We would constantly be scrutinizing and questioning our beliefs. We would spend our lives figuring out what to believe, instead of just believing. Our beliefs manifest into actions, and William Clifford argues in his essays and testimonies that we should not believe on insufficient evidence, yet he makes a great point saying we would universally be skeptics if we were to doubt everything; we would constantly be afraid to move forward.
I believe you do need sufficient evidence to hold a belief or even believe in miracles, Sufficient evidence is an obective claim, in other words, as long as a single subject believes he or she has sufficient evidence, then they determine whether or not it is suffiece. And to counter the opinion of "alot of beliefs have similarities." an athiest beliving there is no god can have the same amount of evidence as a person that does believe in a god, however each religion has some type of code, a book, or scripture depicting the religion, and for those believers this is sufficient evidence for them. Questioning a belief may infact serve as a positive for a person, the constant want of knowledge and the truth may lead to more drive and passion for a person in their life to find the truth. Saying that believing something without sufficient evidence is not a person thinking for themself, but often a case of "bandwaggoning". for instance, a christian may not go to church but believe in a god because his neighbors, family or community believes it is so.
There are always beliefs that cannot be proven or dis-proven, no matter how much "evidence" there is. Our individual beliefs are unique and tailored for each person. You can't always look to believe something with 100% certainty, mainly because there might not be enough evidence surrounding the topic. If you needed absolute evidence to believe anything, Santa Claus, The Easter Bunny, and all other childhood fantasies would not exist. This is where imagination and faith come in to play. People who need to have concrete facts to form beliefs will be over thinking every single fact that they come across. Our beliefs manifest into actions, and if we spend all of our time figuring out whether we should believe something or not, that is time wasted that we could have used actually acting on our beliefs.
If a person does not believe something with 100% certainty, then there is always a probability of what they believe is wrong. If someone has 60% of evidence towards a subject then there is a 40% chance that what they believe is wrong. Now a person is walking around with constant doubt and uncertainty because of the missing proof. If a person is 100% sure that something exists or that miracles are real then there isn't a doubt in their mind, and I'm sure you as a person has better clarity and peace of mind when you believe something through and through without a doubt in your mind. And we believe these childhood fantasies because our parents discuss these things with us when holidays come around. As kids our parents are our most important source of help and reliance. If they say, "be good or Santa clause wont visit you for Christmas." We are not concerned with the impossibility of Santa clause, we are concerned with the repercussions for bad behavior, in turn believing Santa clause. As we grow older however, since we become more reliant on ourselves, we begin to realize, (with evidence) that Santa Clause can not be possible, or the Easter bunny, tooth fairy etc. Santa Clause is never mentioned in the bible yet Christian parents force that idea upon their children. Being young and believing something is possible with no evidence because of the environment or community a child lives in. but believing something is ludicrous unless a person has 100% fact in the matter.