A very good question. In this world, without such help it is impossible for anyone to unite with the divine energy. In the Puranas there are people who have united with this divine energy independently without any aid. Undoubtedly this is true. However, it is impossible now. Why is it so? There are numerous reasons.
First of all, to directly achieve union with God you should be in a state where you can perform various meritorious deeds without any influence from the subtle impressions of his past actions (samskaras, tendencies). In reality however reaching this state is a very gradual progression. Currently, you are even devoid of patience. This world you are living in is causing you plenty of confusions and is putting you in a great dilemma and instability. It is out to destroy you. Your mind runs from hither and tither every moment. It demands fulfillment of all desires. It wants this and it also wants that. This is a bad world full of enemies. How will you conquer them all?
That is why it is advisable to take the help of a spiritual Self-realized Guru. Under His guidance complete your puja, disciplines and spiritual practices. These are aids that get you closer to God. This too progresses gradually. There is no guarantee that you will be able to unite with the Almighty within this birth itself. Perhaps you could be successful in your next birth; perhaps after 10 births. No one knows. You have no authority to demand that you need it in this birth- just now, this minute and so on. The first step in this path is to develop extreme patience. Getting a human birth is itself extremely rare. Take a Guru’s help. Begin with puja, dhyana, yoga etc.
-Glimpses of Bhaktimala 4