How deep must we go in the particulars of what we believe? Is it just the Cross and the events surrounding or is there more?
In any case where we are not carefully grounded in truth we are vulnerable to either temptation or doubt. Succumbing to either (both being essentially the same anyway) leads us into a weak or sinful state in which we can compromise more and more of our life in Christ.
Truth is doctrine. Use the same words, wisdom, truth, doctrine, knowledge when you’re studying.
Truth is tied tightly with our relationship with God:
Psalm 25:5 Lead me in your truth and teach me, for you are the God of my salvation; for you I wait all the day long.
Psalm 86:11 Teach me your way, O Lord, that I may walk in your truth; unite my heart to fear your name.
The Spirit leads us in truth.
John 16:13 When the Spirit of truth comes, he will guide you into all the truth, for he will not speak on his own authority, but whatever he hears he will speak, and he will declare to you the things that are to come.
Seriously, 2 Timothy 3:16 is the summary for what we must consider when we’re wondering how much we need to believe. The whole passage which ends with 3:16 is critical to understand the scope of this verse.
2 Timothy 3:16 All Scripture is breathed out by God and profitable for teaching, for reproof, for correction, and for training in righteousness,