Evangelist Billy Graham has warned that one of the devil's most successful schemes is to convince people he doesn't even exist and said it's important to understand he is just as much at work today as he was years ago.

In his nationally syndicated advice column, the founder of Samaritan's Purse responded to reader who asked why it seems we no longer hear about Satan: "Was talking about the devil just kind of a passing fad?" the reader asked.

Graham explained that the Bible's warning is still true: "Your enemy the devil prowls around like a roaring lion looking for someone to devour" (1 Peter 5:8).

"While we should never make the devil the sole focus of our attention (for only Christ is worthy of that honor), we do need to be alert to his schemes and on guard against his attacks," the evangelist said. "Satan's primary goal is to block God's plans in every way he possibly can."

Sometimes, Graham explained, Satan's attacks are very open and obvious, but often he works in hidden and subtle ways, seeking to deceive people and turn them away from Christ.

"Jesus said that when the devil lies, 'he speaks his native language, for he is a liar and the father of lies' (John 8:44)," he said.

The 98-year-old Baptist minister continued: "It's been said that one of the devil's most successful schemes is to convince people he doesn't even exist-and that's true. After all, if you don't think he exists, you won't be on guard against him. But he does exist, and he'll do everything he can to keep you from Christ and His will for your life."

In a survey conducted last year, Gallup found that while nearly 90 percent of Americans believe in God, only 61 percent believe in Satan.

"Gallup asked the question that includes the 'not sure about' option in random rotation with questions about belief in four other religious concepts: angels, Heaven, Hell and the devil," reported Gallup.

"Americans' belief in all of these is lower than their belief in God, ranging from 72 percent who say they believe in angels to 61 percent who say they believe in the devil, with 12 percent unsure on both. Belief in these four concepts is down at least marginally from when last measured in 2007, following the same pattern as the trend in belief in God using this question format."

Earlier, Graham said it's important remember that while Jesus has defeated the devil, he is still very powerful - and determined to destroy all of humanity.

"He is a very powerful spiritual being who is absolutely opposed to God, and he will do everything he can to block God's plans," Graham said. "He tempts, he deceives, he destroys and he even kills when it suits his purpose. The Bible says, 'Your enemy the devil prowls around like a roaring lion looking for someone to devour. Resist him' (1 Peter 5:8-9)."

However, by Jesus' resurrection from the dead, He overcame the power of sin and death and Satan and hell, Graham said.

"And some day his victory will be complete; Satan will be bound and his power destroyed, and Christ will rule forever and ever," he concluded. "Is your hope and trust in him?"