A prominent stock market forecaster sees the S&P 500 climbing 52% in two years' time.

Laszlo Birinyi, founder and president of Birinyi Associates, says the S&P can reach 3,200 by 2017. On Tuesday afternoon, the S&P was in the 2,090 level.

"Most people don't realize that we are now in the second greatest S&P rally in history, and we are actually ahead of the 1990 rally," Birinyi told CNBC. "And if the market continues to gain 11 basis points a day as it has for the last six years, two years out or so, we're going to be over 3,000."

He said the troubles facing Greece and China should not be a cause for concern. "What we're really trying to tell people is to stay with it. Don't let the bad news shake you out," Birinyi advised investors.

In recent months, a volatile Chinese stock market and Greece's debt crisis have hogged the headlines. But for Birinyi, the news is mere "noise" that should not affect the U.S. stock market. "There's no reason why we can't keep on going."

For the next three to six months, Birinyi expects the S&P to rise to 2,240. So far, it has gone up only 2% this year.

There would be no significant drop in price, the bullish investor said, although he conceded there might be a market correction through a sideways movement over an extended period of time.

Compared to specific sectors, Birinyi sees individual stocks like Chipotle, Google, and Visa more attractive. He said those stocks would continue to reap gains.

But when it comes to Apple, Birinyi is puzzled as to why the world's most valuable company has been losing value. Over the past five days, it has dropped almost 6%. "It is a concern to me because I don't know what's going on," he said.

For some market watchers, Birinyi's forecasts are too optimistic.

Rich Weiss, a senior portfolio manager at American Century Investments, told CNBC the U.S. economy could not support such a strong growth in the market.

Weiss noted this year's gross domestic product is not likely to exceed 3%, and there's a possibility the Federal Reserve would tighten monetary policy.

Meanwhile, Mark Luschini, chief investment strategist at Janney Capital Management, does not see a huge climb from earnings growth either. Instead of going up or down, the stock market could be moving sideways, Luschini told CNBC.

On the other hand, Bill Fleckenstein, a short seller who correctly predicted the 2007 financial crisis, was not as optimistic, saying the "market could crash entirely" in the coming months.

Birinyi began forecasting gains in late 2008. In March the following year, the S&P plummeted to its lowest level in more than a decade.