Yes...a person can be a Christian without understanding why the cross was necessary.
Do you want my understanding of the cross?
Of course, I went through all the hoops of understanding the cross.
All the arguments with Christians, for believing in Jesus' words,
rather than in the cross, and in His death, as they say to.
Most people don't even distinguish between Jesus' cross
and the Roman cross He was hung upon,
so it is all confusing to the newbie.
All that seems important to those with "understanding" is that Jesus died for them,
so much so, they often forget to mention that He rose again.
And that He is alive for us, right now.
There aren't many men in History who didn't die,
and a lot were crucified by the Romans, and by others.
So how will just believing these things about Jesus save you?
And the crucifix was government property.
Belonged to Julius Caesar.
Is an implement of torture unto death.
Was the instrument used to kill out Lord Jesus.
Jesus' cross, on the other hand, was to do the works of the Father.
He laid down His life well before He was crucified, to keep the commandments,
to love us according as God commanded,
and that's why the Pharisees and High Priests had to do away with Him.
So He died for their sins. They were the sinners that murdered Him.
But He rose again.
And this was so men might know He was sent by God,
and that they might believe in Him, and henceforth keep His words.
So I believe in Him, the things that spoke, and not in the preaching of the cross.
Crosses are wooden, and cannot preach.
But men make the cross into an image for us to worship.
Sanctify the Lord.