Christians

The short answer to the OP is: You can't. No one alive today was alive when the Christian bible claims that Jesus was alive. We therefore cannot conclusively verify his existence. End of story.

@brutal

Yet we can verify the existence of Jesus because Jesus is The Truth, and we know The Truth is real.

And if the church that followed Jesus isn't evidence of the so called "historical Jesus", there is obviously nothing that will satisfy your standard of evidence.

Default to disbelief.

No we cant

If you embrace epistemological nihilism, you can't verify anything because even seeing isn't believing.

But the church that followed Christ certainly proves his existence, and indeed, the church is the body of Christ.

That is not proof

Whatever that means.

You know what a body is.

Meaningless.

You being unable to perceive a meaning is not proof of meaningless.

It seems meaningless to you. That doesn't mean it is meaningless. It is certainly not meaningless to me, and neither is it meaningless to the church.

define church.

"The community of the Church is the locus of salvation for mankind; it is truly the Ark in which mankind may be saved from the flood of corruption and sin. In it, Christians sacramentally work out their salvation with fear and trembling (Phil. 2:12), worshipping the Holy Trinity in spirit and in truth. The Church is the pillar and ground of truth (I Tim. 3:15) and thus may be relied upon in the Christian's struggle to apprehend the one truth for himself. The Church is eternal, and the gates of Hell will never prevail against it (Matt. 16:18)."

Still not exactly sure what you mean by "church:. An organization? The people comprising it?

It is The Orthodox Catholic Christian Church as a whole. That is the people, the organization, the church tradition.

Given its flesh from The Virgin Mary, with Christ as our head. We are the body of Christ.

You could call this a mystery, and it is part of the church's experience.

Not sure why someone who believes they have experienced God would call out Christians, makes no sense. Unless you think only your version is real. Which makes you just as bad.

Because Jesus took me and changed my life completely.  

A good reason to believe Jesus is real, but j6 asked

Absolutely everyone of your utterances are the words of men, you have no words from your god. You believe in the words of man only.

I guess the misunderstanding on my part is the vagueness of the term "know". "knowledge" is not just information, it is a intimate experience with the subject or object. Theologically, we talk of a man knowing his wife, we talk of knowing God. We talk of God's foreknowledge of all things. In each of these cases, knowing is not just information but much more than that. Even in legal circles we talk of "carnal knowledge" in a similar fashion. 

Yet, it seems that you consider the OP to be using the term in the sense of "information" only.  How can we know anything? Is there a standard to which we agree? I can only speculate in relation to most things in this world and its history. I can never really know and nor can anyone else. Sometimes people opine that "all things are possible". I don't subscribe to that point of view. Not without qualification anyway. 

I think the historicity of Jesus is fairly well established by most credible historians. After all that is part of the question as well. Jesus is not defined. I would also take the view that anyone saying that they knew the miraculous stories of Jesus as real would be hard put to demonstrate so. And also those who wish to prove he is divine. Hence my response which I personally have experienced. 

I have said elsewhere that the evidence, of which I include the Biblical record inter alia, indicates that Jesus not only died, but rose from the dead. I take the view that there is sufficient reason to concur with the conclusions of the NT and that the possible alternate theories do not contain sufficient unity nor plausibility. Yet, I also acknowledge that prejudice runs rife on both sides of the question. 

So I apologise that I responded with a subjective belief as you understand and not an objective  reason as you suggest the question asked. Given that every person is subjective - and objectivity impossible as such, how can we know anything with absolute assurance? How do we know that our spouse or that our parents love for us is real? How do we know that the government has the best interest of its citizens at heart? How do we know that logic and reason are proper methods of addressing anything? How we know that we exist? "I think, therefore I am", hardly refers to a tree, so do trees exist? 

If the question is simply asking the question: what measure do I use to know that Jesus is real, then my initial response is adequate although not complete.