jewish folks why is so hard the conversion to judaism?

[secret_garden]

I have read rabbis telling the people sometimes no and they have to insist but reading in the Bible Noemi or ruth converted to judaism and she adopted the God of Israel but now it's hard and you have to study many things.. and sometimes rabbis say no..and after that you have some rituals like a specie of baptism and you have to answer some questions well that was I read and not at all rabbis convert to judaism, there are special rabbis and I read the converters are not very acceptable in the jewish community, they cannot emigrate to israel.. just the people who were born as jewish is that true?