God is the First and the Last in Isaiah 44:6 (and 41:4, 48:12 etc.) and Jesus Christ Himself claims to be the First and the Last in Rev. 1:17-18 (and 22:13 cf. Rev. 21:7-8). This title is exclusive to Yahweh and likely means Yahweh is the first God and the last God - the one true and living God. Jesus must be God ontologically! Believe in THIS Jesus or you will perish in your sins (John 8:24).
And also Surah 57:3 of the Qur’an refers to Allah as “the First and the Last, the Most High and the Most Near.” Jesus applied this exclusive title of Deity to Himself!
Some helpful videos:
'A Biblical Case for the Trinity in 5 minutes' : http://bit.ly/1TQ5awo
'The Trinity in a nutshell' : http://bit.ly/1Rnq0Q8
'Acts 2:38: Baptism for salvation? No!' : http://bit.ly/1ogIaIZ
'The original Nicene Creed, modern translation with Scripture references' : http://bit.ly/1XGpajc
'Was the early church mostly oneness?' : http://bit.ly/20o6vdg
'A Brief History of Oneness Pentecostalism' : http://bit.ly/1TteUbh
'The apostle John was a Trinitarian' : http://bit.ly/1UBBF03
'Demonstrating the eternal Son from Scripture': http://bit.ly/1X6Ak4u
'Three persons in one context (verses)' : http://bit.ly/1UPK28f
'Does "Let Us Make Man" Prove the Trinity?' : http://bit.ly/1TUoFBw
'Jewish Trinitarians?' : http://bit.ly/29VHt12
'The oneness of the Trinity' : http://bit.ly/2aZKYaZ
'Debate: Trinity vs. Oneness (Smith vs. Ritchie)' : http://bit.ly/25uMkBi
Please support me and my ministry on Patreon: https://www.patreon.com/trinityapologetics ANY amount would go a long way especially since I live in the Philippines. Even $1! I have plans to get married and enter full time ministry some day.