The South Yorkshiremen got off to a horrendous start down in Kent, conceding twice within four minutes of Saturday's League One contest kicking-off.
But those early goals from Jordan Graham and Vadaine Oliver were quickly cancelled out as the visitors rallied.
Centre-half Tom Anderson headed home a 19th-minute James Coppinger cross from the right, before the latter finished neatly from Josh Sims' lay-off to level matters.
"I think that was a good performance, personally. I think it's a good point. I was disappointed with the two goals but overall it's a pleasing point," Butler reflected.
"We're climbing a mountain after that first four minutes. We knew what they were gonna do. We knew their game-plan. We prepared the players, they knew what was coming. We just didn't defend the first two balls well enough, but after that I thought we were incredible at defending balls into the box.
"The number of headers we won, first balls, second balls, blocks, it was great to see the work ethic and togetherness of the lads.
"I always thought, even at 2-0 down, that we'd get back into the game. I said it to the staff on the sideline 'we'll still get back into this', so credit to the players. It showed the desire not to let set-backs affect us
"There was a never-say-die attitude and I thought we could maybe have sneaked it at the end."
Saturday's result means that promotion-chasing Rovers have now taken just two points from the last 12 on offer, but keeps them fifth in the League One standings with 12 matches left to play.
Gillingham: Bonham, Jackson, Ogilvie, Cundy, Tucker, Dempsey, MacDonald (O’Connor 78), O’Keefe (McKenzie 78), Graham, Akinde (Lee 71), Oliver. Subs not used: Bastien, Willock, Johnson, McKenzie, Woods.
Doncaster Rovers: Jones; Halliday, Wright, Anderson,Horton; James, Smith; Sims (Lokilo 69), Coppinger (Richards 61), Okenabirhie (Gomes 88); Bogle. Unused substitutes: Balcombe, Robertson, John, Greaves.
Referee: W Finnie (Bedfordshire).