Stocks soared after Fed Chair Jerome Powell's Wednesday speech, in which the central bank chief said interest rates were "just below" neutral, a reversal from his October stance that they were "a long way" from the Fed's goal.
But for Cramer, there's a more complicated hurdle that "we need to jump to reach the bullish promised land," he said on "Mad Money."
"We've checked off the Jerome Powell box. He won't be the cause of the major slowdown, not after today," he said. "However, we still have the G-20 summit — China — and this is actually a much tougher nut to crack."
President Donald Trump and Chinese President Xi Jinping are expected to meet at G-20 to discuss U.S-China trade policy. The summit of the world's economically developed nations will take place in Buenos Aires, Argentina.
The two countries have traded tariffs on each other's exports in the latter half of 2018, leaving investors unsure of what will become of U.S.-China relations. U.S tariffs on roughly $200 billion worth of Chinese goods are set to rise from 10 percent to 25 percent at the end of the year, and Trump has threatened further rounds of tariffs.
"We don't know what the president's going to do" at the summit, Cramer said. "My educated guess? Trump will say that he's not satisfied with what the Chinese are doing so far, so he's going to ... increase [the tariffs] from 10 to 25 percent. However, he'll also extend an olive branch, which is that he'll be willing to hold off on applying his tariffs to the other half of China's U.S.-bound exports."
Cramer, who agrees that China's unfair trading practices warrant some sort of retaliation but doesn't necessarily think the Trump administration's plan is the best bet, said a no-deal result at G-20 would only create a small "hiccup" in the rally.
But "if I put my stock hat on, I want to see some sort of deal with China because that's good for business," he said. "Maybe they lift a lot of their trade restrictions and we don't need to raise the tariff to 25 percent. Wouldn't that be great for the market? But I don't think the Chinese will bite."
But with the Fed issue now at bay, Cramer said the most toxic issue for the stock market was now gone and, depending on G-20, stocks could see brighter days from here.
"Regardless of what the president's saying about him, Powell is a rigorous thinker, a flexible leader, a good guy, and today, he may have given both the economy and the stock market a new lease on life, provided that the president's G-20 foray doesn't end with the White House getting even more bellicose on China," the "Mad Money" host said. "The last thing the stock market needs is an iPhone tariff. Today, though, was a win. A big, fat W. Enjoy it."