You could do web searches in places like Google, YouTube, Amazon, GotQuestions.org with keywords like: Christian faith reasons to believe and find a variety of answers. But...you came here.
Personally, I think that Christian faith began in me as early as ages 3-7. Mother, grandmother and church were influences. By age 7, I was already aware of Christian concepts like:
* God knows all things.
* God can do all things.
* God is everywhere.
* There is an eternal heaven and hell
* Father, Son and Holy Spirit
* Good and evil
* Sin and righteousness
* Love and hatred
* Jesus spoke the Sermon on the Mount
* Jesus healed lame, deaf, blind and dead
* Ten Commandments
* Lord's Prayer: Our Father Who Art In Heaven
* Crucifixion of Jesus Christ
* Resurrection of Jesus Christ
* Ascension of Jesus Christ to heaven
* Prophesied Return of Jesus Christ
* God answers prayer
* There is a final judgement awaiting all
* There was a beginning to the earth and universe.
* There will be an end to the earth and universe.
* God knows all things; Nothing can be hidden from God
* It is appropriate to pray: Lord, have mercy.
* God requires us to show mercy to others.
* God cares for the sick, the poor, little children
* God is loving.
* God is righteous and holy.
I did some re-thinking and drifting after high school but then re-committed to Christ around 5 years later. To a significant degree, the concepts above have stayed with me.
Ultimately, Almighty God must change our inner being with his grace and Holy Spirit.
Experientially, the Christian should resonate with expressions like "The statutes of the LORD are right, rejoicing the heart." (Psalm 19:8).
There is much interdependence in nature and ecology. Space, sun, sea, soil, rock, plants, animals, male, and female all have intricate relationships and dependencies with each other. I would find it unbelievable that such intricate order and relationships happened without a Designer, Creator and Sustainer. I would find it unjust and discouraging if there were no accountability and no justice in the end. Mercy is what I hope to inherit eternally rather than strict justice and recompense. The search for knowing God better is a joy and adventure without limits.
Since at least age 7, I have known these words of Jesus Christ from the Sermon on the Mount:
Ask and it will be given to you. Seek and you will find. Knock and the door will be opened unto you. (Matthew 7:7)