Is it contrary to any Christian belief or doctrine to believe that Jesus deceives us in order to protect our souls?

This is what Jesus said:

36 “But concerning that day and hour no one knows, not even the angels of heaven, nor the Son, but the Father only. 37 For as were the days of Noah, so will be the coming of the Son of Man. 38 For as in those days before the flood they were eating and drinking, marrying and giving in marriage, until the day when Noah entered the ark, 39 and they were unaware until the flood came and swept them all away, so will be the coming of the Son of Man. 40 Then two men will be in the field; one will be taken and one left. 41 Two women will be grinding at the mill; one will be taken and one left. 42 Therefore, stay awake, for you do not know on what day your Lord is coming. 43 But know this, that if the master of the house had known in what part of the night the thief was coming, he would have stayed awake and would not have let his house be broken into. 44 Therefore you also must be ready, for the Son of Man is coming at an hour you do not expect. (Matthew 24:36-44)

Jesus told his disciples that only the father knows when he (the Son) will return. There is no deception here! He says it could be soon or not.

There are places in Scripture where prophets are told to seal up a mystery until the end - Daniel (8:26,9:24,12:4,12:9) and the Apostle John (Rev. 10:4) come to mind. If it were a matter of keeping a secret, Jesus would have said, "I know, but I am not authorized to tell you." God is not shy when it comes to saying that there are things that He choses not to reveal.

But, you say, if Jesus is God, then he must be omniscient! And if omniscient, he must know when he will return. Jesus is omniscient, but when he spoke those words to the disciples, he spoke the truth as a man who had taken upon himself certain limitations, as Paul explains in Philippians 2:

5 Have this mind among yourselves, which is yours in Christ Jesus, 6 who, though he was in the form of God, did not count equality with God a thing to be grasped, 7 but emptied himself, by taking the form of a servant, being born in the likeness of men. 8 And being found in human form, he humbled himself by becoming obedient to the point of death, even death on a cross. 9 Therefore God has highly exalted him and bestowed on him the name that is above every name, 10 so that at the name of Jesus every knee should bow, in heaven and on earth and under the earth, 11 and every tongue confess that Jesus Christ is Lord, to the glory of God the Father. (Philippians 2: 5-11)

(Note: Theologians debate how much and in what ways Christ emptied himself and how those limitations were divided between his human and divine natures, but that is a huge question.)

In Revelation, Jesus is now glorified and the seven seals are broken, revealing God's plan for the end. Jesus has broken those seals and now knows the time, and he told John to keep it a secret. This means that the savior and the church (with John as representative) - not God alone - are keeping this secret, out of obedience and for reasons known best to God.

(Note: Preterists, partial preterists and historicists would agree that Jesus has already opened the seals. Some dispensational, pre-tribulation rapture, or other interpretations may view the opening of the seals as still a future event.)

There is a second way to take all this: Jesus comes for us on the day we die. That means that the day of his return varies from person to person, soon for some, far off for others, with one big arrival at the end of time when those still living meet him.

_{I know I should probably reference these, but I'm going to appeal to common knowledge}

Before answering, I just want to re-emphasize two central teachings that are common to the vast majority of Christianity:

• It's safe to say that almost every denomination, and almost every major division within Christianity agrees that God does not and cannot lie. I'm sure there are exceptions to that rule, and agnostics/atheists may balk at the idea, but for the most part that's accepted teaching for the vast majority of Christianity.
• Most (but not all) Christian denominations and traditions accept the Diety of Jesus. In other words, Jesus is God. (There are exceptions.)

If the second point is true, then to say that Jesus lies is to say then God lies. And the first point flat out denies that.

So, according to Scripture, as understood by the overwhelming majority of Christianity, it is absolutely a heresy to say that Jesus would deceive us to protect our souls.

And most denominations that I am aware of state that Heresy is a sin.

So yes, to the overwhelming majority of Christianity, it would be be accurate to say that it's a sin to believe that Jesus would lie to us to protect our souls. Not only does it go against "any other Christian belief or doctrine" it goes against two central, almost universally held Christian beliefs/doctrines. The doctrine of God's character and the doctrine of Christ's Diety.