What changes or supports your doctrine?

I was raised in a church that dwelt heavily on predictive prophesy, eschatology. The question of saving faith was tinged with a lot of emotionalism and sentimentality also. I was taught a lot of doctrine, but then by providence, I encountered people and writings that pointed me to Scripture that contradicted some of my beliefs and impressions. Here are a few and how God forced me to make a choice: do I believe His word, or do I follow man-made ideas and reasoning read into his word?

My early belief: 'kingdom of heaven' and 'kingdom of God' are 2 different things, 'kingdom of God' referring to a future 1000 years where Christ rules from Jerusalem.
Scripture: Comparing parallel passages in Matthew, Mark & Luke; I saw Matthew writing in Jewish style used the phrase "kingdom of heaven" while Mark & Luke would use "kingdom of God" quoting the exact instance. I then saw Jesus used the terms interchangeably: “Then said Jesus unto his disciples, Verily I say unto you, That a rich man shall hardly enter into the kingdom of heaven. And again I say unto you, It is easier for a camel to go through the eye of a needle, than for a rich man to enter into the kingdom of God.” (Mt 19:23-24 AV)

My early belief: Israel had never possessed all the land and promises given to Abraham, so the future 1000 year kingdom was needed to complete the fulfillment of the promises.
Scripture: “And the LORD gave unto Israel all the land which he sware to give unto their fathers; and they possessed it, and dwelt therein. And the LORD gave them rest round about, according to all that he sware unto their fathers: and there stood not a man of all their enemies before them; the LORD delivered all their enemies into their hand. There failed not ought of any good thing which the LORD had spoken unto the house of Israel; all came to pass.” (Jos 21:43-45 AV) Also: Josh.23:14-16; Neh. 9:22-25; Gn. 15:18 compared to 1 Kgs. 4:20,21

My early belief: God promised to David that his descendant, meaning Jesus, would sit on his throne, certainly a prophecy to be taken literally, a throne in Jerusalem.
Scripture: “Men [and] brethren, let me freely speak unto you of the patriarch David, that he is both dead and buried, and his sepulchre is with us unto this day. Therefore being a prophet, and knowing that God had sworn with an oath to him, that of the fruit of his loins, according to the flesh, he would raise up Christ to sit on his throne; He seeing this before spake of the resurrection of Christ, that his soul was not left in hell, neither his flesh did see corruption. This Jesus hath God raised up, whereof we all are witnesses. Therefore being by the right hand of God exalted, and having received of the Father the promise of the Holy Ghost, he hath shed forth this, which ye now see and hear.” (Ac 2:29-33 AV)

My early belief: I believe in Jesus Christ so I am saved, possess eternal life and I can't lose it. Then I was challenged that was true only as long as I held my faith to the end and endured, but I could reject my faith and lose my salvation.
Scripture: “For unto you it is given in the behalf of Christ, not only to believe on him, but also to suffer for his sake;” (Php 1:29 AV)
[Ah ha, my faith/belief was not something I had that I contributed to my salvation; it was given me just as the trials and tribulations I kept enduring by God's free grace!]
“Being confident of this very thing, that he which hath begun a good work in you will perform [it] until the day of Jesus Christ:” (Php 1:6 AV) [Wow! What comfort, that gift of grace by which God began his work in me he will perform until the day of Jesus Christ!"]
“For it is God which worketh in you both to will and to do of [his] good pleasure.” (Php 2:13 AV) [It is of God that I will and do his pleasure!]
“My sheep hear my voice, and I know them, and they follow me: And I give unto them eternal life; and they shall never perish, neither shall any [man] pluck them out of my hand. My Father, which gave [them] me, is greater than all; and no [man] is able to pluck [them] out of my Father’s hand.” (Joh 10:27-29 AV)
MY FAITH IS IN JESUS CHRIST, NOT IN MY OWN FAITH AND/OR WORKS!!

I will add, I do believe a truly regenerate person continues in faith and reject this idea of pointing back to some conversion experience years ago that does not show any evidence today.

“For God so loved the world, that he gave his only begotten Son, that whosoever believeth in him should not perish, but have everlasting life.” (Joh 3:16 AV)