BY THE HOLY SPIRIT
The beginning of a Believer's Kingdom Foundation is made up of conviction, understanding and experience as, in His mercy and grace, the Holy Spirit works.
Everyone who has repented and received Christ has done so by faith which "... comes by hearing and hearing by the word of God," Romans 10'17.
And then this:
"But after that the kindness and love of God our Saviour toward man appeared,
Not by works of righteousness which we have done, but according to his mercy he saved us, by the washing of regeneration, and renewing of the Holy Ghost;
Which he shed on us abundantly through Jesus Christ our Saviour;
That being justified by his grace, we should be made heirs according to the hope of eternal life," Titus 3'5-7.