The first issue addressed by the Lotus Sūtra can be summarized as follows:

Should śrāvakas and pratyekabuddhas remain unable to attain buddhahood? Is it permissible to cut them off as a group with low aspirations? Isn’t that against the concept that Mahāyāna Buddhists should aspire for the attainment of buddhahood not only for themselves, but also for a wide range of others?

The Lotus Sūtra responds to this issue by teaching the “opening the three vehicles to reveal the One Vehicle” idea in Chapter 2, “Expedients,” and the “obtainment of buddhahood by the people of the two vehicles” based upon this idea. …

Here is the second issue addressed by the Lotus Sūtra:

In Mahāyāna Buddhism various buddhas appear. These include Śākyamuni Buddha, Bhaiśājyaguru or Medicine Master Buddha, and Amitābha or the Buddha of Infinite Light. This means many Buddhas exist. In the text of the Lotus Sūtra, many buddhas appear who existed in the past, exist now, and will exist in every direction. What is the relationship between these buddhas?

The Lotus Sūtra responds with the teaching of “opening the near to reveal the far” in Chapter 16, “The Duration of the Life of the Tathāgata.” In this chapter, Śākyamuni Buddha explains that in a far distant time in the past, he achieved buddhahood. Since then and into the eternal future he continues to work towards the salvation of others as the so-called Eternal Buddha. He also states that the buddhas who existed in the past, exist now, and will exist in every direction are all parts of the Eternal Buddha. In other words, the Eternal Śākyamuni Buddha is fixed as the basic unifying Buddha for all the buddhas who existed in the past, exist now, and will exist in every direction.