Scripture for thought
Hebrews 12:14-15 Pursue peace with everyone, as well as holiness, without which no one will see the Lord. See to it that no one falls short of the grace of God, and that no root of bitterness springs up to cause trouble and defile many.
1 Corinthians 10:1-13 (1-5, 9-13) grumbling, idol worship and unbelief.
Hebrews 5:11-14; 6:1-12
For further study here is an article, https://focuspress.org/2017/03/21/bible-says-falling-away/
https://youtu.be/pzg7riAm59g