When you think “The Bible says it, I believe it, that settles it”, you are, I’m afraid, functionally illiterate. If I ask how certain you are in your description of undoubtedly the central symbol in Christendom, “Absolute” may be your response if this is your mentality.
“STAUROS denotes, primarily, an upright pale or stake. On such malefactors were nailed for execution. Both the noun and the verb stauroo, to fasten to a stake or pale, are originally to be distinguished from the ecclesiastical form of a two beamed cross.”
W. E. Vine, Vine’s Expository Dictionary of Old and New Testament Words, 1981, Vol. 1, p. 256.
Vine describes our familiar symbol is of Chaldean origin, adopted from the pagans by Christendom in the third century C.E. as a symbol of Christ’s impalement.
To “Walk humbly with your God” includes your psychology, and certitude is psychology alone. It includes your own estimation of what you think of the Bible and how you approach reading it.
Now image once more that I ask about your certitude in your understanding of salvation.