@Lees
To make a long story longer (LOL)....
I'm guessing you're working with the "Vicarious Atonement" theory of the atonement. And YUP one of the problems with that is it really has no use for the Resurrection. Yet Scripture seems to suggest that Easter is THE most important thing; the resurrection THE most important part of Jesus' work. That theory works great to explain the incarnation/perfect life and the Cross/death of Jesus but leaves Easter as little more than "well, it's done - see you later."
You'll find much more here in the Christus Victor view (although that too has it's problems). Easter here means VICTORY, the defeat over sin, death and the power of Satan. It means that His victory is ours.... His life is ours... as He rose over sin and death, in Him so do we.
Here's how it seems to me. Each of the atonement theories is biblical, each has a lot going for it, although each one - individually - has problems and ultimately fails (as your Vicarious Atonement view does here). But TOGETHER, they are helpful. And that's what Christians tend to do... they use them together - going to the one that best explains a single point. I suspect you'll find a lot here using Vicarious for His life and death, the Christus Victor one for Easter (that's common in modern Protestantism). And I'm pretty okay with that. BUT....
We know this: Jesus IS the Savior. He does it ALL. 100%. We contribute abolutely nothing (we are simply blessed by HIS work applied to us). What work? Well, several things: His incarnation and perfect/moral life. His suffering and death on the Cross. And His resurrection from the dead. All of that. Together. All of it essential, absolutely necessary - we would be lost without it. Now, WHY does that save us? Why is each part necessary? Exactly WHY? Well.... there we simply don't have a full answer. THAT Jesus saves - yup, we know that. THAT this involves those things, yesuree. But WHY each of those things - that's not really clear. The various Atonement Theories attempt to explain that - but none (in and of itself) really does.
@Lees I think it important to remember that the Bible exists to Show us Salvation (Gospel) and Show us how to Live (Law). And it does a good job of that! It's not a philosophy book and it's not a science book (although it may touch on both to do the above). And it's certainly not a Q&A book. It's purpose is not to answer all our questions (even good ones). God tells us what we need to know - not necessarily what we want to know. He tells us what we need to know to accomplish it's purpose. The result is sometimes we just don't know something. We are left with MYSTERY. The Bible tells us to be "stewards of the MYSTERIES of God." NOT "appoint yourself to be God's answer man for every question you may have."
This website is typical but while I agree with her on every point, it doesn't really answer the question of why it was NECESSARY for our salvation; she kinda skirts around that:
7 Reasons Why Easter Is All Important To Christians
Blessings
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