Netziv (Shemos 13:9): Don’t be surprised that G-d requires us to do so many mitzvos and techniques to acquire bitachon (trust) and emuna (faith) in G-d’s Providence. The fact is that it is known that the Jews do not readily accept authority until they are forced as we see by the plagues. That is why G-d took us out of Egypt with a strong hand because it was not easy for us to accept His dominance. This is seen in the medrash which discusses, “The Jews did not listen to Moshe because of their irritability and stress of their enslavement.” The medrash explains that they didn’t want to listen because they were immersed in idol worship. In other words, the medrash means that in fact they did not want to be redeemed. In truth though the first time when they were told that G-d had remembered them and sent Moshe to save them that all of them believed and bowed down. The reason that they responded differently the second time was that at that time He informed them that He wanted to be their G-d. In other words, they had no problem acknowledging G-d except when it meant they would be supervised and controlled by G-d depending on their behavior. Thus, they didn’t want to accept G-d’s control until G-d took them out of Egypt against their will. Something which is difficult for a person to accept requires many activities to implant in his heart.