The 1001 save file offers a range of benefits to players, including:
: This tool on Speedrun.com automatically backs up your current saves and installs a fully-unlocked Dead God file.
If you only want unlocks but want to keep your own death count, item tracking, etc., you can use a save editor (e.g., Isaac Save Editor by Hyphenet). This lets you merge a 1001% file with your personal stats—but that’s beyond basic installation.