…he who does not believe God has made Him a liar, because he has not believed the testimony that God has given of His Son. – 1 John 5:10

Oh, unbeliever, it appears to be nothing to you that Christ has died. His wounds attract you not. His groans for His enemies have no music in them to you. You turn your back upon the incarnate God who bleeds for men, and in so doing you shut yourselves out of hope, judging yourselves unworthy of eternal life.

Furthermore, the willful rejection of Christ is an insult to God the Father. “He that believes not has made God a liar, because he has not believed the record that God gave of His Son.” God has Himself often borne testimony to His dear Son. “Him has God the Father set forth to be a propitiation for our sins.” In rejecting Christ, you reject God’s testimony and God’s gift. It is a direct assault upon the truthfulness and lovingkindness of the gracious Father when you trample on or cast aside His priceless, peerless gift of love.

As for the Blessed Spirit, it is His office here below to bear witness to Christ. In the Christian ministry, daily the Holy Spirit cries to the sons of men to come to Jesus. He has striven in the hearts of many of you, given you a measure of conviction of sin, and a degree of knowledge of the glory of Christ, but you have repressed it, you have labored to your utmost to do despite to the Spirit of God. Believe me, this is no slight sin. An unbeliever is an enemy to God the Father, to God the Son, and God the Holy Ghost. Against the Blessed Trinity in Unity, O unbeliever, your sin is a standing insult. You are now to God’s face insulting Him, by continuing an unbeliever. ~ C.H. Spurgeon

https://www.blueletterbible.org/comm/spurgeon_charles/sermons/1012.cfm