“Blessed are the pure in heart, for they shall see God." (Matt. 5:8, ESV)

Note also the statements in John such as:

"No one has ever seen God; the only God, who is at the Father’s side, he has made him known." (John 1:18, ESV)

"And this is the judgment: the light has come into the world, and people loved the darkness rather than the light because their works were evil. 20 For everyone who does wicked things hates the light and does not come to the light, lest his works should be exposed. 21 But whoever does what is true comes to the light, so that it may be clearly seen that his works have been carried out in God.” (John 3:19–21, ESV)

If anyone’s will is to do God’s will, he will know whether the teaching is from God or whether I am speaking on my own authority. (John 7:17, ESV)

Jesus said to him, “Have I been with you so long, and you still do not know me, Philip? Whoever has seen me has seen the Father. How can you say, ‘Show us the Father’? (John 14:9, ESV)

When Christopher Hitchens debated the existence of God with William Lane Craig, he made the statement, "I don't want any deity telling me what to do." This seems to be a key reason for disbelief.

“Blessed are the pure in heart, for they shall see God." (Matt. 5:8, ESV)

This possibility is based on how Jesus describes seeing God as something occurring in this life in the Gospel of John.

... he [Jesus Christ] has made him [God the Father] known." (John 1:18b, ESV)

I left out the first part of the above verse because the issue over textual variation distracts from this question.

Jesus said to him, “Have I been with you so long, and you still do not know me, Philip? Whoever has seen me has seen the Father. How can you say, ‘Show us the Father’? (John 14:9, ESV)

It is also based on a person's willingness to come to Christ as expressed in the following.

"And this is the judgment: the light has come into the world, and people loved the darkness rather than the light because their works were evil. 20 For everyone who does wicked things hates the light and does not come to the light, lest his works should be exposed. 21 But whoever does what is true comes to the light, so that it may be clearly seen that his works have been carried out in God.” (John 3:19–21, ESV)

If anyone’s will is to do God’s will, he will know whether the teaching is from God or whether I am speaking on my own authority. (John 7:17, ESV)

When Christopher Hitchens debated the existence of God with William Lane Craig, he made the statement, "I don't want any deity telling me what to do." This seems to be a key reason for disbelief.