The Lord is ever-present. However when He manifests on this earth as a human being, His physical and material body must pass away just as other humans. The Lord however lives on. He lives on through His idols (Murtis), through the scriptures such as Vachanamrut and He also lives on through His spiritual successor.
Lord Shree Swaminarayan Himself has stated in the Vachanamrut (Vadtal 18) that every paramhansa (sant) and devotee should know and understand the Guruparampara (lineage of the Gurus).
Shree Swaminarayan Bhagwan then stated that His Guru was Shree Ramanand Swami. Shree Ramanand Swami was given diksha (initiation as a sant) by Shree Ramanujacharya, and hence Shree Ramanujacharya was the Guru of Shree Ramanand Swami. This was the Guruparampara.
A very important question needs to be asked at this point. Shree Swaminarayan Bhagwan is the supreme Lord, so why did He see a need to make a Guru for Himself? Lord Shree Swaminarayan taught by example. By making a Guru Himself, Lord Shree Swaminarayan has indicated the importance of a Guru. He has indicated that we should all have a Guru. Jeevanpran Swamibapa says that without a Guru, you cannot attain knowledge. "Guru veena gnan nahee."
Thus it is vital that we should all recognise the direct lineage from Shree Swaminarayan Bhagwan - the Guruparampara.
Sadguru Shree Gopalanand Swami, by the express wish and in the presence of Lord Shree Swaminarayan, in front of thousands of His followers-saints and devotees, was handed the helm of the entire supreme Swaminarayan faith. His every word was to be implicitly obeyed as the command of the Lord Himself and those who did not obey were to be regarded as not being of the Swaminarayan faith. This fact is recorded in many scriptures written by the "Nand" Saints of the time.
Sadguru Shree Gopalanand Swami handed the leadership to His true disciple Sadguru Shree Nirgundasji Swami who in turn after introducing the Swaminarayan faith to Jeevanpran Abji Bapashree (will-manifest of Lord Swaminarayan) passed the divine power to Sadguru Shree Ishwarcharandasji Swami who in turn gave it to His Divine Grace Jeevanpran Shree Muktajeevandasji Swamibapa.
Swamibapa, handing over the helm of the faith to Shree Purushottampriyadasji Swamishree Maharaj, said that Lord Swaminarayan and all the previous leaders shall be the doers of the works of His Holiness Swamishree. This is the true and direct spiritual lineage of Lord Swaminarayan - the Guruparampara.
"Guru Guru to sahu kahe, pan Guru ek Sahajanand,
Pragat malyane hathaj jhalyo, teno chhe anand."
Shree Swaminarayan Bhagwan is ever present through these Acharyas and is ever working through these Acharyas, and so Swamibapa says that our true Guru is therefore Shree Swaminarayan Bhagwan Himself.
These are the Acharyas of Shree Swaminarayan Gadi, through whom absolute salvation can be attained. Swamibapa says, that the true Guru is only Shree Sahajanand (Swaminarayan Bapa Swamibapa) - only those who have found this Supreme Lord and who have resorted unto the shelter of Lord Swaminarayan - attain supreme bliss and happiness.