To a certain extent, this world is "controlled" by the devil. That's why he's referred to as "the god of this world". Humans found it "hard" because humans are made with a much lower intelligence than the angels (such as the most crafty snake in Eden). For the same reason, humans are completely captive on Earth without exception. That's actually why Jesus is needed for human redemption.
The nature of Faith is never something "hard". Humans think that it's "hard" because they are blinded, in a sense just as put, "the god of this world has blinded the minds" of men. Faith is the fundamental element for each and every single human to reach each and every single truth of any kind. God simply demands the same faith you've employed to reach every single truth you can reach in your life time.
By and large, humans are incapable of reaching a truth which doesn't lie within the reach of our own 5 senses. Faith remains the only way to reach a truth of any kind which doesn't lie within the direct reach of our 5 senses (that means it's about all truths you can reach on a daily basis). Fundamentally, you don't need any evidence to tell what's going on in this world, you only need a media which fed you with "news" for you to swallow as "facts". That's how faith works for everyone.
Moreover 5 senses are incapable of reaching the future, nor capable of reaching the past. We need "faith in testimonies" to reach both. God's message is legitimately in a history which humans basically lack the ability to write, to keep and to convey. Among the thousand civilizations and nations ever existed on the surface of Earth, only the Chinese and the Jews can have a rather complete set of history. All other histories are either broken or non-existent. From after fact, if God has to convey His truth through a history (and He does) He can only choose between the Chinese or the Jews. That's the one fold meaning of what a Chosen People is.
It's for a reason that God demands humans to approach Him with faith, just the same way as how humans reach each and every single truth (outside the direct reach of our 5 senses). It's nothing "hard" but one thing which is fundamental to humanity. This demand is closely tied to the Covenant which requires humans to be saved by Faith and Faith alone. It means humans are demanded to reach the truth of God as "something" lying outside their direct touch with the 5 senses (though we all can have a 6th sense to reach God through the Holy Spirit, and to keep a "contact" with God and Jesus). That is, if God shows up for your 5 senses to touch, you won't be able to be saved by Faith.
However, if God doesn't show up completely humans will be clueless about who God is. He thus allows eyewitnesses/prophets to have a "more direct" touch for testimonies/Jewish history to be formed, then for the rest to believe with Faith. Faith together with repentance are employed for the assessment to see if a human is correctable or not, after all of us sinned to our very death. Faith and repentance define if one is correctable. If one is correctable then he can be holy in the end to live with the sin-compatible God in eternity.
All Satan's effort is the make this process of Faith assessment "hard", yet the harder the test is the more precious will be those who can successfully pass the test. The test is "hard", but God will get the best of best out of the hardness of Faith.