<%= link_to user_omniauth_authorize_path(:google_oauth2), class: 'btn btn-block btn-social btn-google-plus', 'data-no-turbolink' => true do %> Sign in with Google <% end %>

Or use the form below

<%= simple_form_for(resource, as: resource_name, url: session_path(resource_name) ) do |f| %> <%= f.input :email, required: true %> <%= f.input :password, required: true %> <% if devise_mapping.rememberable? -%> <%= f.input :remember_me, as: :boolean %> <% end -%> <%= f.submit "Sign in", class: 'btn btn-primary' %> or <%= link_to "Sign up", new_registration_path(resource_name) %> / <%= link_to 'Forgot password', new_password_path(resource_name) %> <% end %>