The draft amendment is part of a set of suggested changes. It enshrines Russians' "faith in God," adding that marriage as a "union of a man and a woman," a wording in sync with Putin's long-stated opposition to same-sex marriages.
Ahead of these proposals, the Russian-Orthodox church, with which Putin has closely aligned himself, had asked to add a reference to "God" to the constitution, causing huge controversy among critics. They refer to the long-standing communist tradition and the strict division between church and state.
Many others criticised the proposed amendment, arguing that it is inappropriate considering Russia is a multi-denominational country.
Experts suspect that Putin used this proposal to divert attention from other critical draft amendments, which could expand his powers.
Nationwide vote in April
The Kremlin-controlled parliament quickly endorsed Putin's draft in the first of three required readings last month, and is set to give it the final approval next week, setting the stage for a nationwide vote on April 22.
Putin first proposed amending the constitution in January's state-of-the-nation speech, saying it is necessary to broaden the powers of parliament and bolster democracy. Kremlin foes have described the proposed changes as part of Putin's efforts to remain in charge after his current six-year term ends in 2024.
Following up on proposals from a Kremlin working group that worked in parallel with lawmakers, Putin on Monday presented 24 pages of additional amendments for the second reading set for March 10.
Proposal to prevent "giving away" Crimea
The president also responded to a working group member's suggestion to add wording that would prevent any future Russian ruler from giving away Ukraine's Crimea — annexed from Ukraine in 2014 — or any other territory. He added an amendment that prohibits surrendering any part of Russian territory and outlaws making calls for that.
Another proposal underlines a special status of Russians as a “state-forming” ethnic group while pledging to protect the nation's other ethnic groups.
And in sync with proposals to outlaw disparaging the Soviet role in WW II victory, Putin added an article pledging to protect “historic truth” and forbid "belittling the people's heroic protection of the Motherland."
The amendment comes as Russia prepares to celebrate the 75th anniversary of victory in World War II — the nation's most important holiday.
The new set of amendments doesn't offer any clue, however, what position Putin may take to continue calling the shots after his term ends. The 67-year-old Russian leader has been in power for more than 20 years, making him the nation's longest-serving leader since Soviet dictator Josef Stalin.