Since there is no singular New Age theology, but rather a variety of associated beliefs and tendencies. Many of the "New Age" approaches to religion assume reincarnation or transmigration of souls. The existence of past lives entails some effects of past on present, particularly the concept of "karma" or the way in which good or bad thoughts, habits, or deeds in the past affect what will happen to you in the future. Also, since many of the New Age groups believe that reincarnation transcends species, i.e. that souls exist in all living creatures, many New Agers believe that this entails vegetarianism and respect for animals.
It is impossible to explain your beliefs - it's all based on a book which we know to be true because we believe it. Anyone can just say, "but that book is fake, it's a lie".
We can't prove it's true, but here's some points that might help:
1. Did you know that the Bible uses the words: "Thus says the LORD", or "God said" or something like that, over 4400 times? Unbelievable, isn't it. And the more amazing fact is that these words are found in most Bible books, which were all written at different times and by differrent people. It's just amazing.
2. Everything in the Bible fits with everything else. Don't believe them when someone tells you nothing makes sense. If someone wants to find problems with the Bible, all you need to do is twist the words. But in actual fact, the Bible does make sense. Isn't it amazing that the prophets can foresee events that will come in hundreds of years time? The prophets even mentioned that Jesus will be called Jesus, hundreds of years before he was born, and that He would be born in Bethlehem, and that John the Baptist will pave the way before Him. Prophets during the time of the kings prophesied of Nebucadnezzar, even mentioning him by name saying he would capture them and take them to Babylon. The Bible was definitely inspired by God.
3. There are quotes from all over the Bible found everywhere in the Bible. Matthew is constantly quoting from the prophets. Doesn't that say something about the truthfulness of Scripture?
4. The most amazing thing I find in the Bible is the symbolism found in the Old Testament, symbolising what would happen in the New Testament. For example, Moses was a symbol of Jesus, as mediator, because he mediated for the Israelites in the desert, just as Jesus is doing for us today. Another symbol is the sacrifices and offerings which all point to the ultimate sacrifice. The flood symbolised baptism. The blood of circumcision symbolised the shedding of Christ's blood. Moses spend forty days up on the mountain and Jesus spent forty days in the desert. There is so much symbolism that the Old Testament and New Testament go hand in hand, even though they were written thousands of years apart and in different languages.
Looking at these four aspects, it is impossible to say that someone made up the Bible. The Bible is so neatly woven, so complementing, and so perfect, that only God could have inspired it.